Mechanical and fluid system and method for the prevention and control of motion sickness, motion-induced vision sickness, and other variants of spatial disorientation and vertigo

ABSTRACT

A non-electronic head-worn system for providing visual inertial head orientation information to a person is disclosed. The system comprises a head-worn unit that displays at least one orientation reference symbol to the person wearing the unit wherein the orientation reference symbol stays in a fixed visual position for the person when the person&#39;s head changes orientation. The system comprises an optical element located in the optical path between the user&#39;s eye and the orientation reference symbol, such as a lens, mirror, a prism, a beam splitter, a retro-reflector, or any other device or medium that can change the appearance or apparent location of an image. The system further comprises a pitch indicator that gives visual pitch information to the person and/or a roll indicator that gives visual roll information to the person. The pitch indicator and the roll indicator are responsive to a pendulum, a rolling element, or a fluid in a reservoir. The pitch element and the roll element do not use electricity or electronics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.14/020,450 filed Sep. 6, 2013, which is hereby incorporated by referencein its entirety.

BACKGROUND

The present invention generally relates to head worn devices and methodsfor mitigating or preventing motion sickness. Motion sickness caninclude vertigo, simulation sickness, gaming sickness, spatialdisorientation, dizziness, vision induced motion sickness or vectioninduced motion sickness in 2-D, 3-D, or 4-D environments, including theviewing of displays such as with operation of remote devices, insimulators, medical imaging, surgical training or operations, virtualenvironments, scientific visualization, space use, or gaming. The headworn devices can be attachable and detachable from another deviceattached to the head, such as a helmet or glasses; the head worn devicescan be integrated into another device attached to the head, such as ahelmet or glasses; or the head word devices can be standalone devicesattached to the user's head. Mitigation and prevention of motionsickness more specifically relates to the use of a visual reference toprevent conflicting sensory mismatch between the visual, proprioceptive,and inner ear senses. The visual reference may be controlled through amechanical or fluid system responsive to gravitational forces. Theprevention and control of motion-related sickness and spatialdisorientation can minimize symptoms of nausea, vomiting, and factorsthat compromise human performance in motion-related environments.

Motion Sickness occurs because of the mismatched sensation with what isseen compared to what is felt and what is perceived in the inner ear.There are many different types of provocative motion environments thatcan induce motion sickness, motion-induced vision sickness, and othervariants of spatial disorientation and vertigo. Often these provocativeenvironments are intensely stimulating but for many people with motionintolerance, the provocative motion environment may be subtle.Provocative motion environments can be associated with locomotion suchas ships, hovercraft, aircraft, automobiles, and trains. The complexaccelerations generated by fairground amusements, such as swings,roundabouts (merry-go-rounds), roller coasters and so on, can be highlyprovocative. Astronauts/cosmonauts can suffer from motion sickness(space-motion sickness) when they first make head movements in theabnormal force environment (weightlessness) of orbital flight.Provocative motion environments can also be experienced by moving visualstimuli, without any physical motion of the observer. Typical examplesof visually stimulating environments include participating in virtualreality platforms or systems. Virtual reality (VR), Augmented Reality(AR), Multi-Dimensional (MD) and Synthetic environmental systemsencompasses a set of technologies that place the user in acomputer-generated, three-dimensional environment and all can encompassa provocative motion environment for the user. Augmented reality mixesthe physical with the virtual, layering computer-generated objects andinformation onto the real world. These types of environments can createa VR experience that truly fools the brain. The feeling of experiencingreality while in a VR, AR, MD and synthetic systems is a very profoundone, as the brain interprets sensory data as though actuallyexperiencing an event. For many using these platform systems, the resultis visually induced motion sickness. Simulator sickness is anotherexample of motion sickness, and simulator sickness in virtual realityenvironments (VRE) has become an important issue. Most provocativemotion environments cause three distinct, but possibly related,responses: reflexive eye movements (EM), sensory conflict (SC), andpostural instability (PS). A provocative motion stimulating environmentcan be defined as being immersed in an environment where the user canexperience vestibular stimulation, (such as with vehicular motion),visual stimulation (such as with simulator, VR, AR, MD, or othersynthetic visual systems), postural or proprioceptive disturbances (suchas with experiencing vertical vibrations with frequencies between0.16-2.0 Hz) and even with sequentially based low frequency auditorysignals. Some examples of provocative motion environments includevehicle use, an AR (augmented reality environment), a multi-dimensionalenvironment, a synthetic or computer generated synthetic environment,and/or a visual induced environment, such as watching motion while theuser is motionless.

Mismatched sensation of what is seen compared to what is felt and whatis perceived in the inner ear can occur any time when the brainperceives that the body is in motion (through signals originating in thelabyrinth and transmitted to the brain by the vestibular nerve), but themotion sensed does not match what the eye can see and verify. Forexample, a passenger traveling along a winding road in a vehicleexperiences linear and angular accelerations as the vehicle travelsaround a curve. The response of the vestibular sensing system to theacceleration caused by the motion of the vehicle will not match thevisual perception unless the person is constantly viewing the road sothat the perception of the person's inner ear matches that which isvisually perceived. Passengers in a vehicle who are doing other taskssuch as reading will have a visual perception that does not match thesenses of their inner ear and may experience symptoms of motionsickness. Additionally the sensory mismatch can occur when the eyeperceives motion, but the labyrinth does not provide confirming signalsto the brain (such as watching a rocking boat while motionless). It canaffect anyone and depending on the degree of provocation can be quitedisabling. Balance receptors respond to gravity, velocity and changes invelocity. Some of the inner ear receptors sense linear or tilt motionand other sense rotational movement.

Motion Sickness, spatial disorientation and vertigo have beenacknowledged as a widespread problem, affecting a significant portion ofworld population to varying degrees. Researchers report that up to 60%of the population has some motion intolerance. It has been reported thatmotion sickness affects nearly one third of all people who travel byland, sea, or air. Individuals are affected daily by motion sickness andspatial disorientation while riding in automobiles, trains, buses,planes or other transport. The Greeks provided the first writtenhistorical account of motion sickness. The Roman Cicero claimed he wouldrather be killed in battle than suffer the tortures of nausea maxis.Motion sickness has even been used as a form of punishment. One of theworld's most famous mariners, Admiral Lord Nelson reportedly neveradapted to motion sickness. Napoleon's General Carbuccia refused to usecamels for Napoleon's army, because of the issues with motion (2) EvenLawrence of Arabia is reported to have experienced Camel sickness.

It is also known that some people are more susceptible than others; forexample, women are more sensitive to motion than men by a ratio of about5:3. Some are more susceptible due to physical reasons such as age.Studies show a significant genetic contribution to a propensity tomotion sickness. It has been well observed that poor ventilation, badodors, smoking, eating large fatty meals and alcohol can make motionsickness more pronounced. Susceptibility to motion sickness begins atabout age two, and for most will peak in adolescence and declinegradually. However, many adults remain highly sensitive caused by anymotion, particularly when combined with either an absence of a visualreference or to significant levels of visual stimuli. In fact, aprovocative visual stimulus has been shown to be the most influentialcause of motion sickness symptoms. Reading in a moving vehicle, abruptlymoving the head (such as looking down) while a vehicle is moving canprovoke symptoms. Fear, anxiety and other psychological factors cancontribute to the onset of motion sickness. Some people can get sickjust thinking about an upcoming trip or flight.

For those who experience the symptoms, the result is often disabling,with nausea, vomiting, sweating, and unsteadiness, while feeling cold,clammy and disorientated. In addition, the term “sopite syndrome” wascoined to refer to the apathy, passivity, and lack of concentrationcharacteristic of motion sickness.

Of the 12.6 million passengers who cruise annually, an estimated 20% ormore become seasick. The occurrence of motion sickness can approach 100%in cruise ship passengers on rough seas. Seasickness, a common form ofmotion sickness, is also frequent among naval personnel, where 60% to90% percent of inexperienced sailors can suffer from seasickness.Experienced crewmembers are not immune. Up to 60% of experiencedcrewmembers have been affected in these conditions. This becomes a majorproblem in modern seamanship in which small crews are responsible forthe operation of sensitive and sophisticated equipment. During theinvasion of Normandy, in World War II, the seas were reportedly veryhigh causing the landing crafts to pitch and yaw, like a kite in awindstorm. The soldiers were lying and sitting in flat bottomed craftsand were using huge buckets for vomiting and urinating, which soonoverflowed after boarding. As thousands of men were lying in the vomit,urine and rain they debarked in a state of terror, which was compoundedby their symptoms of seasickness, and attempted to perform at a highlevel in order to survive in combat. Many of these soldiers had toovercome the most debilitating effects of motion sickness to survive.There are additional volumes of data that document the severe effect ofmotion sickness on human performance of even basic tasks.

Spatial disorientation and motion sickness are significant problems inaviation. In motion provocative environments, spatial disorientation andmotion sickness cause not only a loss in human performance (affectingcognitive and motor skills), but also a loss of expensive aircraft andhuman life. Thousands of deaths have been attributed to aviationaccidents caused by being spatially disoriented. In a review of aviationmishaps from 1987-1997 by the Aviation Safety Foundation of the AircraftOwners and Pilots Association, there was an average of one fatal SDaccident every 11 days in the United States. These accidents haveresulted in a fatality rate of 91% in the General Aviation (GA)community and a 69% fatality rate in the U.S. Military. There are over650,000 civilian pilots in the United States alone. Non-instrument ratedpilots who fly into the clouds historically have 178 seconds beforeground impact. The death of John F. Kennedy Jr. was an example of aspatial disorientation accident and unknown to many were thirty otherreported crashes that same day, with at least one other due to spatialdisorientation. According to FAA statistics, SD and loss of situationalawareness causes 15%-17% of fatal general aviation crashes annually.More significantly, 9 out 10 SD mishaps result in a fatality. From1980-2000, the USAF experienced 1,087 aviation fatalities with over 14%(172) directly attributed to SD at a cost of over $1.54B. A recent studyhas shown that almost 90-100% of aircrews have reported at least oneincidence of spatial disorientation (SD) during their flying careers. SDaccounted for 11-14% of USAF mishaps and a mishap fatality rate of 69%,with risk of SD significantly increased in helicopters andfighter/attack aircraft and at night. The most frequent experienced SDepisodes are “leans” (92%), loss of horizon due to atmosphericconditions (82%), misleading altitude cues (79%), sloping horizon (75%),and SD arising from distraction (66%). The Air Force Safety Center FY93-02 mishap analysis reported that Class A mishaps resulted in 243destroyed aircraft, 310 fatalities, and an economic loss of $6.23billion. Airsickness has also been identified as a flight trainingissue. A motion sickness history questionnaire obtained from studentpilots in the Air Force revealed an incidence of airsickness of 50%. Ina questionnaire to B-1 and B-52 bomber crewmembers, it was reported tobe a frequent occurrence among non-pilots in both aircraft, andexperienced crewmembers were more likely to report an impact on theirduties.

Space motion sickness is experienced by 60%-80% of astronauts during thefirst 2-3 days in micro gravity and by a similar proportion during theirfirst few days after return to Earth. Up to 90% of astronautsexperienced spatial disorientation during reentry and landing of theshuttle, with prevalence proportional to the length of the mission.Exposure to micro gravity rearranges the relationships among signalsfrom visual, skin, joint, muscle, and vestibular receptors. Congruencebetween vestibular signals and those from other receptors, as well asbetween the vestibular otolith and semicircular canal receptors, isdisrupted by the absence of gravity. This lack of congruence betweensensory exposure to provocative real or apparent motion leads to theprogressive cardinal symptoms of terrestrial motion sickness. Spacemotion sickness may vary slightly with flushing more common than pallor,stomach awareness, malaise, loss of appetite, and sudden vomiting, oftenwithout prodromal nausea. The only remedy to space motion sickness atthis moment is drug therapy while stationed in space, a decidedlynon-optimal solution. Additionally during training for space flightstudents aboard the zero-G flight simulator routinely experience motionsickness. When people go up into space, many will immediately get spacesickness, according to NASA's Biomedical Research and CountermeasuresProgram. While a few astronauts are apparently immune, most canexperience symptoms ranging from mild headaches to vertigo and nausea.In extreme cases prolonged vomiting can make an astronaut dehydrated andmalnourished. Motion sickness remains a persistent problem in spaceflight. Proposed etiological factors in the elicitation of space motionsickness include fluid shifts, head movements, visual orientationillusions, Coriolis cross-coupling stimulation, and otolith asymmetries.Space sickness relieves itself after about 3 days, for some althoughindividual astronauts and cosmonauts may have a relapse at any timeduring their mission and continue to take medication, which can altertheir cognitive and motor function. For those personnel in sub-orbitalflights performing a research job or experiment for a client, theycannot afford to be sick or disoriented or distracted. They have four tofive minutes on a sub-orbital flight to get a job done. If afflictedwith space sickness human performance is compromised. In the privatespace tourism companies it is a known fact that passengers are verylikely to have space sickness, or its more scientific name, SpaceAdaptation Syndrome (SAS). Even with medication, most astronautsexperience it when they go to space to varying degrees, from mild nauseaor a headache to vomiting. SAS is a main reason that extra-vehicularactivities (EVA) outside of the space shuttle are done only after a fewdays in space, as vomiting inside a space suit is lethal. Someastronauts who show an exceptional tolerance to motion sickness whenflying jets suffer the worst symptoms upon arriving in space. Astronautsreturning from extend space flights routinely have to learn to reorientthemselves in the terrestrial environment. Motor and cognitive skillsare often observed to be severely degraded during the re-acclimationperiod. This is due to the sudden reintroduction of gravitational cuesand stimulus of proprioceptors. The time needed to re-acclimate to theterrestrial environment is about three days per week in space.

Vestibular disorders affect an estimated 20% of the general population.90 million Americans (42% of the population) will complain of dizzinessat least once during their lifetimes, and 80% of these complaints willhave a vestibular component. There are more than 10 million physicianvisits annually for dizziness or balance complaints (Source: NationalBalance Centers/Vestibular Disorders Association), with a cost ofgreater than one billion dollars per year. Postural control requires acomplex interaction of visual and proprioceptive sensory inputsproviding external orientation reference frames while the internalreference frame is provided by the vestibular system. Persistentvestibular dysfunction can occur following a variety of insults to thevestibular system, including infections, ototoxicity, trauma, chronicear pathology, tumors, Meniere's disease, surgery and other idiopathiccauses. Acoustic tumor surgery and vestibular nerve section, performedfor disabling vertigo in patients with Meniere's disease, usually resultin rapid compensation. However some patients, particularly non-Meniere'sdisease patients, have a prolonged period of unsteadiness withoutcompensation for a long period of time. The resulting disability can bedevastating. It has also been shown that postural instability precedesmotion sickness with provocative visual stimuli. All these vestibularimpairments cause disequilibrium, blurred vision, disorientation, andvertigo, which in turn cause dysfunction in many activities of dailyliving and in social interactions that traditional medical treatmentsmay not address.

Medical rehabilitation, overcoming chronic illness, recovery fromsurgery, and recovery from trauma represent additional applications.Presently, 10 million patients receive balance (vertigo) medicalrehabilitation therapy costing $1 billion annually. Reasons fortreatment are due to disease affecting the vestibular organs,rehabilitation from surgery on the balance organs, recovery from traumato the head and rehabilitation in patients learning to use prostheticsin the lower extremities. Clinical tests conducted by the inventorfunded by the National Institutes of Health (NIH) resulted in 96%effectiveness in resolving balance issues associated with these variousmaladies. Regarding overcoming chronic illness, many patients with theNIH test group with chronic balance disorders were able to return tofunctionality after enduring years of other ineffective treatments. Thevisual display reduced the average number of clinical visits from 25rehabilitation treatments to 5 and in several cases proved to be theonly effective treatment the patient had ever experienced. Regardingrecovery from surgery, within the NIGH test group, the visual displayproved to reduce the average number of clinical visits from 25rehabilitation treatments to 5 and in several cases proved to be theonly treatment effective. Regarding recovery from trauma, head traumaand injury to the inner ear often result in temporary balance problems.The loss of proprioception with injuries to extremities can also resultin loss of balance. In tests the visual display greatly shortenedrehabilitation and recovery times and in some cases was the onlytreatment effective to aid recovery due to head trauma, vestibularinjury and limb injury. Regarding rehabilitation using prosthetics tolower extremities, physicians associated with the US Army Center for theIntrepid, based at Brook Army Medical Center in San Antonio Tex. reportthat many soldiers who have suffered injury to the lower extremities oramputation have balance issue while learning to use prosthetics. This isdue in part to loss of proprioception inputs associated with the loss ofthe limbs and new weight distribution associated with the prosthetics.It is hypothesized our technology will greatly shorten rehabilitationtime by providing strong visual cues to offset the loss of sense oftouch due to limb loss and aid balance while learning to use the newlimbs.

Simulation sickness, or simulator sickness, is a condition where aperson exhibits symptoms similar to motion sickness caused by playingcomputer/simulation/video games. Simulation sickness or gaming sicknesscause symptoms quite similar to that of motion sickness, and can rangefrom headache, drowsiness, nausea, dizziness, vomiting and sweating.Research done at the University of Minnesota had students play Halo forless than an hour, and found that up to 50 percent felt sick afterwards.In a study conducted by U.S. Army Research Institute for the Behavioraland Social Sciences in a report published May 1995 titled “TechnicalReport 1027—Simulator Sickness in Virtual Environments”, out of 742pilot exposures from 11 military flight simulators, “approximately halfof the pilots (334) reported post-effects of some kind: 250 (34%)reported that symptoms dissipated in less than 1 hour, 44 (6%) reportedthat symptoms lasted longer than 4 hours, and 28 (4%) reported thatsymptoms lasted longer than 6 hours. There were also 4 (1%) reportedcases of spontaneously occurring flashbacks.” Simulator sickness isanother example of motion sickness, and many military pilots havereported at least one symptom following simulator exposure. In a studyof Coast Guard aviators undergoing flight simulator testing, 64%reported adverse symptoms during the first simulator flight and 39% didso during the last flight. 36% of pilots reported motion sickness whentraining on a Blackhawk flight simulator.

More recently, simulator sickness in virtual environments (VE) hasbecome an important issue. Virtual reality is already a populartechnology for entertainment purposes, and both the U.S. Army and Navyare interested in the training applications of virtual environments.However, some users of VE experience discomfort during, and sometimesafter, a session in a simulated environment, in equivalent fashion tosimulator sickness already noted for flight and driving simulators.Similarly, in casual gaming, a number of modern electronic games featurea virtual control interface. These displays are often not see-throughand present highly motion provocative visual displays.

Motion sickness due to virtual reality is very similar to simulationsickness and motion sickness due to films. In virtual reality, however,the effect is made more acute as all external reference points areblocked from vision, the simulated images are three-dimensional and insome cases stereo sound that may also give a sense of motion. Theworld's most advanced simulator, the NADS-1, located at the NationalAdvanced Driving Simulator, is capable of accurately stimulating thevestibular system with a 360-degree horizontal field of view and 13degree of freedom motion base. Prior studies have shown that exposure torotational motions in a virtual environment can cause significantincreases in nausea and other symptoms of motion sickness. CounterVertigo in Virtual Pilot Vehicle Interface. Operators of unmanned aerialsystems (UAS) routinely experience spatial disorientation due to limitedvisual cues in sensor control displays. Further, experiments using avirtual pilot vehicle control interface, where the pilot controlled theUAS based on visual cues derived directly through sensors (placing thepoint of view on the nose of the aircraft) versus via CRT controldisplays led to cases of SD and motion sickness. It is believed ourtechnology will prevent SD/MS in both UAS PVI environments.

Vision Induced Motion Sickness, such as the motion sickness due to filmsand other video is a type of sickness, is particularly prevalent whensusceptible people are watching films on large screens such as IMAX butmay also occur in regular format theaters or even when watching TV. Forthe sake of novelty, IMAX and other panoramic type theaters often showdramatic motions such as flying over a landscape or riding a rollercoaster. There is little way to prevent this type of motion sicknessexcept to close one's eyes during such scenes or to avoid such movies.In these cases, motion is detected by the visual system and hence themotion is seen, but no motion or little motion is sensed by thevestibular system. Motion sickness arising from such situations has beenreferred to as Visually Induced Motion Sickness (VIMS). Movie-inducedmotion sickness has become more prevalent due to new cinematographictechniques. For example, there are claims that “The Hobbit: AnUnexpected Journey” has caused motion sickness and nausea among viewers.The film having been shot using 3-D and new 48 fps (frames per second)technology, double the standard rate of 24 fps that has been used toshoot films since 1927. Additionally, in regular format theaters,another example of a movie that caused motion sickness in many peoplewas The Blair Witch Project. Theaters warned patrons of its possiblenauseating effects, cautioning pregnant women in particular. Blair Witchwas filmed with a handheld camcorder, which was subjected toconsiderably more motion than the average movie camera. Home movies,often filmed with a hand-held camera, also tend to cause motion sicknessin those that view them. The cameraperson rarely notices this duringfilming since his/her sense of motion matches the motion seen throughthe camera viewfinder. Those who view the film afterward only see themovement, which may be considerable, without any sense of movement.Using the zoom function seems to contribute to motion sickness as wellas zooming is not a normal function of the eye. The use of a tripod or acamcorder with image stabilization technology while filming can minimizethis effect. 55% of people who watch 3D movies have MS. Following themarket expansion of movies filmed with three-dimensional (e.g. 3D)technology and televisions equipped with 3D displays for the homeentertainment, there has been an increasing concern about possible sideeffects on spectators. It has been suggested that the viewing of 3Dstereoscopic stimuli can cause vision disorders to manifest inpreviously asymptomatic individuals. The prevalence of health outcomeson 3D movie spectators appears to be increasing in domesticenvironments.

Research on professional exposures to virtual reality systems, vehiclesimulators, and stereoscopic displays have reported that several adversehealth effects can be induced by viewing motion images, including visualfatigue (also termed asthenopia), or eyestrain, vection induced motionsickness and visually induced motion sickness (VIMS). Symptoms of visualfatigue induced by images comprise eye discomfort and tiredness, painand sore around the eyes, dry or watery eyes, headaches and visualdistortions such as blurred and double visions, and difficult infocusing. The main physiological mechanism involved with the onset ofvisual fatigue concerns the intense eye accommodation activity of 3Dmovie viewers, such as focusing and converging. It has been argued thateye focus cues (accommodation and blur in the retinal image) target thedepth of the display (or of the movie screen) instead of the displayedscene, generating unnatural depth perception. Additionally, uncouplingbetween vergence and accommodation affects the binocular fusion of theimage. Both processes may generate visual fatigue in susceptibleindividuals. In addition to symptoms of visual fatigue, viewers of 3Dmay experience nausea (nausea, increased salivation, sweating) anddisorientation (dizziness, vertigo, fullness of head). Those symptomsare indicative of VIMS, a condition that may onset during or afterviewing dynamic images while being physically still, when images inducesin the stationary spectator a sense of vection (i.e. illusion ofself-movement). The most accepted explanation for VIMS is the classicalconflict theory based on the mismatch between the visual, theproprioceptive and the vestibular stimuli. In this case, the visualsystem feels vection while the vestibular and proprioceptive systems donot transmit signals consistent with motion. Notably, although VIMS andvisual fatigue are different conditions, they probably share some commonbiological mechanisms.

The specific disturbance deriving from viewing 3D movies has been named“3D vision syndrome” but the relative occurrence of different symptomsin spectators and the individual characteristics that make someindividuals more susceptible than others still remain to be described.Previous research showed that occurrence of self-reported symptoms inyoung healthy adults during or immediately after watching a 3D movie maybe high, although often quickly disappearing once they finished viewing.Factors reported to be associated with VIMS can be categorized into (i)factors associated with the visual stimuli provided to viewers, (ii)factors associated with the position from where the viewers are watchingthe movie and (iii) the psychophysiological conditions of the viewers.Examples reported in literature include (but are not limited to): thecharacteristics of the (moving) images (e.g. the optic flow) such as theearth axis along which the visual field is made rotating, the amplitudeof the field of view, the display angle, the feeling of immersion orpresence, the co-presence of vection, the display types, posturalinstability, habituation, age, gender, and anxiety levels of viewers.Interactions and additive effects among factors may also be present,making difficult to predict the final outcome (if a given individualwill or will not suffer VIMS).

Earlier experiences of visual discomfort observed in 3D display viewersled to the hypothesis that the conflict between vergence andaccommodation stimuli is the cause of such visual discomfort. Controlledexperimental conditions in which the effect of the vergence-focalconflict on visual fatigue could be isolated from other variablesconfirmed such explanation. Additionally, it has been argued that 2Dmovie viewers tend to focus at the actors while the eye movementpatterns of 3D viewers are more widely distributed to other targets suchas complex stereoscopic structures and objects nearer than the actors.This behavior might increase the vergence-accommodation mismatch,increasing the visual stress on 3D spectators. The higher intensity ofvisual symptoms when participants were exposed to the 3D movie comparedto the 2D movie observed in our study could be taken as a large-scaleevidence of such hypothesis. Possibly, a partially different mechanismis involved in the onset of nausea and disorientation related symptoms.Nausea, dizziness and vertigo are connected to vestibular disturbanceand the visual—vestibular interactions and the classical sensoryconflict theory can explain the onset of symptoms in susceptibleindividuals. The public health relevance of VIMS was raised some yearsago in Japan when 36 (out of 294) high school students were hospitalizedfor motion sickness after watching a movie characterized by unexpectedwhole image motion and vibration (the so called Matsue movie sicknessincident). A previous multivariate analysis suggested that seeing a 3Dmovie increases the simulator sickness questionnaire (SSQ) scores.Besides the exposure to 3D, significant predictors of higher SSQ totalscore were car sickness and headache after adjusting for gender, age,self-reported anxiety level, attention to the movie and show time. Theuse of glasses or contact lenses does not seem to increase the risk ofraising SSQ scores. Women with a history of frequent headache,carsickness (and possibly dizziness, which is correlated with the abovementioned variables) may be more susceptible to VIMS than others. Therelationships between motion sickness, vertigo, dizziness, and migraineis well documented and 3D movies may interact with these conditions toproduce more symptoms than 2D movies.

Clearly viewing 3D movies can increase rating of nausea, oculomotor anddisorientation. Analogous to riding a roller coaster, for mostindividuals the increases in symptoms is part of the 3D experience andenjoyment and these experiences is not necessarily an adverse healthconsequence. However, some viewers will have responses that in othercontexts might be unpleasant. In particular, women with susceptiblevisual-vestibular system may have more symptoms when watching 3D movies.Individual variability of the 3D exposure including the length of themovie, the angle of view and the pre exposure baseline conditions arepotential predictors of visual discomfort that may warrant futureinvestigation. As noted by others, 3D viewing may increase task burdensfor the visual system, and susceptible individuals may develop a “3Dvision syndrome”. Due to increasing commercial releases of 3D movies anddisplays for home and professional use it is likely that more peoplewill complain about these symptoms.

The worldwide increasing popularity of commercial movies showingstereoscopic (e.g. three dimensional—3D motion images is documented bythe fact that 3D releases are generating more revenues than the samemovie released in 2D. In parallel with the expansion of digital 3Dcinema systems, several consumer-electronics manufacturers released 3Dtelevisions and displays for the home entertainment. For example, morethan 300 3D videogames are already available for computers and consoles.Stereoscopic displays are becoming also very important for no leisureapplications such as vision research, operation of remote devices,medical imaging, surgical training, scientific visualization, virtualprototyping, and many others. In the near future, it is predictable thatmore and more people will pass increased portion of time (either leisureor work time) viewing 3D motion images, raising concern about the 3Dimage safety and possible adverse side effects on end users.

There are concerns about possible adverse effects of watching novelvisual images and experience of VR, such as photosensitive seizures,visually induced motion sickness (VIMS) and eyestrain. In particular,when a patient watches an image changed based on real-time informationof his head-position, which is sometimes used in VR system, there is apossibility that he watches unexpected images, such as upside-down orrotating, and then he feels VIMS. Since almost all users of therehabilitation system are aged and/or physically weak, mental orphysical stress on them caused by VIMS is typically greater than onhealthy users.

Stereoscopic three-dimensional (3D) displays and the viewing content aredesigned to heighten a sense of immersion and presence for viewers. Asmanufacturers increasingly offer 3D TV models and 3D TV programmingcontent and commercial movies are made available to viewers at home,there is an increasing concern about visual, ocular, and physicaldiscomfort reported by some 3D viewers. The commonly held explanation ofvisual symptoms in 3D viewing is that it stimulates a different vergenceand accommodative demand than encountered in real 3D. The 3D displaysprovide stereoscopic visual stimulation by projecting separate images toeach eye. Each image is a view of the scene from a slightly differentangle, thereby simulating the different views of the eyes in a realscene. Stereoscopic depth provides relative depth information; i.e. itinforms the viewer about the relative (not absolute) distances ofobjects with respect to one another. 4D/5D Theatre Technology: In recentyears, 3D viewing has been accompanied with synchronization of somespecial effects installed in the theatres. When it rains in the movie,the audience also experiences the same. When there's lightening in themovie, the same happens in the theatre. Other effects include wind, fog,smell, sensation etc. These are called 4D effects. Theatres with 3Dviewing, 4D effects and some seat movements are called 4D theatres. Incases of 5D theatres, seats move in synchronization with motion in themovie thus providing immersive experience to the audiences. For this atleast six—directional seat movements are required: left and right rolls;forward and backward tilts; and up and down movements. These theatresshow an excellent integration of 3D technology, audio, motionsynchronization and multiple special effects using specialized software.For synchronization, using special software, movies and seat motion ispre-programmed.

Rotating devices such as centrifuges used in astronaut training andamusement park rides such as the Rotor, Mission: Space and the Gravitroncan cause motion sickness in many people. While the interior of thecentrifuge does not appear to move, one will experience a sense ofmovement. In addition, centrifugal force can cause the vestibular systemto give one the sense that downward is in the direction away from thecenter of the centrifuge rather than the true downward direction. Whenone spins and stops suddenly, fluid in the inner ear continues to rotatecausing a sense of continued spinning while one's visual system nolonger detects motion.

There have been many theories about the cause of motion sickness,spatial disorientation and vertigo. Currently, the sensory conflicttheory appears to be the dominant theory favored by researchers in thatthe majority of investigators agree that it is not solely the movementor movement stimulus that results in motion sickness, but rather aconflict in movement information detected by the different sensorymodalities of the inner ear, vision, and proprioception. A conflict ofvisual and vestibular (inner ear) information, as it relates to posturalcontrol and visual stabilization, is certainly a critical factor.Investigators now also agree that it is primarily an incongruence ofvisual and vestibular sensory information regarding movement andorientation that results in motion sickness. Incongruence between thesemicircular canals and the otolithic organ input has also beenimplicated as the provocative stimulus in seasickness and in the onsetof motion sickness associated with weightlessness. Another contributingfactor which may trigger susceptibility to motion sickness may be themass size differences of the utricular otoconia between the left andright sides in some people, as seen in fish.

Within the sensory conflict concept has arisen an “incongruence in thevisual system” theory, which can be called a Velocity Storage Theory.The vestibular nerve communicates head velocity and estimates of angulardisplacements require further central nervous system processing (i.e.integration). There is some inconsistency between velocity-based ocularstudies and displacement-based perceptual studies. Most oculographicstudies of vestibular function are based on measurements of the slowphase velocity of the eye. If a monkey or man is rotated at constantvelocity in the dark, the velocity of the slow phase of the nystagmusdecays exponentially with a time constant of Fifteen to Twenty seconds(15-20 sec). Direct recordings of the vestibular nerve in monkeys haveshown the head velocity signal, transmitted by the vestibular nerve, hasa time constant of decay of only Seven to Ten (7-10 sec). The durationof the eye velocity curve (i.e. a nystagmus response) is thereforelonger, outlasting the sensation or perception curve. The perception ofangular velocity is based on signals subserved by the brainstem velocitystorage system. Thus the head velocity signal appears to be stored inthe brain and then released onto ocular motor neurons for the generationof nystagmus. Brainstem circuits in the vicinity of the vestibularnuclei, behaving as mathematical integrators, are thought to mediatethis storage process. There is evidence that motion sickness isgenerated through this velocity storage and can be reduced by reducingthe angular vestibular ocular reflex time constant. Others support amulti-factor explanation of motion sickness, involving both sensoryconflict and eye movement.

Ordinarily, eye movements prevent slip of images upon the retina fromexceeding about 4 degrees per second. If retinal image velocity (RIV),commonly called, “retinal slip,” exceeds 4 degrees per second, thenvisual acuity begins to decline and oscillopsia (an illusory movement ofthe stationary world) may result. Pursuit eye movements allow primatesto follow moving objects with the eyes. When a target of interest startsto move, after a latency period of 120 ms, the eye accelerates smoothlyin the direction of target motion to reduce the error between eyevelocity and target velocity, i.e., retinal slip. Eye accelerationincreases with the retinal slip and saturates at a value between 200 and400°/s2 for non-periodic tracking in primates. In the middle of thisacceleration period, a “catch-up” saccade is generated to reduce theerror between eye and target positions that accumulated during thelatency period. The catch-up saccade brings the image of the target onthe region of the retina where visual acuity is the highest, the fovea.In primates, smooth pursuit gain, the ratio of eye velocity to targetvelocity, is close to unity. This indicates that at the end of theacceleration period, eye velocity almost perfectly matches targetvelocity. The period during which eye velocity matches target velocityis often referred to as steady-state pursuit. During steady-statepursuit in primates, eye velocity oscillates around a mean value. Thefrequency of this oscillation varies between 3.8 and 6 Hz and couldreflect the delays inherent in the operation of a visual feedback loop.Retinal image slip promoted by fixational eye movements prevents imagefading in central vision. However, in the periphery a higher amount ofmovement is necessary to prevent this fading. Even when the eye isfixating a point target it is not totally motionless because fixationaleye movements keep it moving incessantly. There are three types offixational eye movements: tremor, drift, and microsaccades. Tremor is anaperiodic, wave-like motion with velocities of approximately 20 minutesof arc/sec and amplitude smaller than the diameter of a foveal cone.Drift movements occur simultaneously with tremor and are larger andslower than tremor, with velocities in the order of 4 minutes of arc/secand mean amplitudes of around 2-5 minutes of arc. This amplitudecorresponds to a movement of the retinal image across a dozenphotoreceptors. Fixational microsaccades, also called ‘flicks’ in earlystudies, are small and fast eye movements that occur during voluntaryfixation. Typically with peak velocities above 600 minutes of arc/sec,their amplitude ranges from 1 to 120 minutes of arc and they carry theretinal image across a width corresponding to several dozen to severalhundred photoreceptors.

Despite this incessant retinal motion, images are perceived as staticand clear. The visual system has mechanisms to deal with movement andthe eventual blur resultant from the retinal image slip caused byfixational eye movements. These mechanisms fail when the amount ofmovement is above their capacity of neutralization. In these conditions,the image is perceived as blurred due to motion smear. An immediateconsequence of blur is a diminution of resolution. Gaze control invarious conditions is important, since retinal slip deteriorates theperception of 3-D shape of visual stimuli. Several studies have shownthat visual perception of 3-D shape is better for actively movingobservers than for passive observers watching a moving object. When astationary viewer is watching compelling moving scene, he or she canreport sensation of self-motion illusion (called vection). Vection hasbeen found to be correlated with levels of visual induced motionsickness (VIMS) and postural status. The correlation between vection andVIMS is consistent with the sensory conflict theory because sickness isgenerated in a sensory conflict situation where a person is reportingillusion of self-motion while remain physically stationary. Thecorrelation between vection and VIMS has led to the term “vectioninduced motion sickness”. One theory linking VIMS with inappropriate eyemovements is consistent with the findings that suppression of eyemovements by fixation can significantly reduce levels of VIMS. It hasbeen hypothesized that the afferent signals in the ocular muscles willtrigger vagal nuclei, resulting in a range of sickness symptomsassociated with the autonomous nervous systems—the nystagmus theory.Because eye movements follow foveal stimulation and vection followsperipheral stimulation, the nystagmus theory indicates that in thepresence of foveal stimulation, sickness will correlate with eyemovements but not necessarily with vection. Since then, there have beencompeting studies reporting the decoupling between vection and VIMS aswell as coupling between vection and VIMS. Some have felt that vectionand motion sickness can be distinct phenomena and have further describedOptokinetic stimulation generating circular-vection, and vectiongenerated during a simulation of forward motion in a car as linearvection. In a prior study using an Optokinetic drum with this technologyit was seen that both vection scores and simulator sickness scores werestatistically significantly lower than when the technology was not used.

Eye fixation has consistently been shown to significantly reduce levelsof visually induced motion sickness (VIMS). The common belief is thatthe reduction in VIMS is associated with the suppression of eyemovement. One study proposed an alternative theory to associate thereduction of VIMS due to eye fixation with the increases in peripheralretinal slip velocity. Results showed that when participants werewatching striped patterns rotating at 7 dps (degrees per second), eyefixation significantly increased the peripheral retinal slip velocityfrom about 2.6 dps to 7 dps and but failed to cause a significant changein the average rated levels of VIMS. However, in the same study,increasing the peripheral retinal slip velocity of moving patterns from2.6 dps to 35 dps in the presence of OKN significantly increased therated levels of nausea from 2.1 (mild unpleasant symptom) to 3.6 (mildto moderate nausea). It might be that when watching patterns moving at 7dps, eye fixation introduced two competing effects: (i) suppression ofeye movement reduced levels of VIMS and (ii) increases in peripheralretinal slip velocity increased levels of VIMS. However introducingfixation into stimulated or a VE environment reduces the foveal slip andmotion sickness. Retinal image slip promoted by fixational eye movementsprevents image fading in central vision. However, in the periphery ahigher amount of movement is necessary to prevent this fading. Theeffects of increased retinal image slip are different for simple(non-crowded) and more complex (crowded) visual tasks. Prior resultsprovide further evidence for the importance of fixation stability oncomplex visual tasks when using the peripheral retina. This technologycan prevent both foveal slip and peripheral retinal slip velocity in aprovocative motion environment.

Mismatches can be caused where there are differences in stimuli asprocessed by the brain. Mismatches can occur where there is motion, orwhere there is no motion. These mismatches may be caused by delays inthe delivery or processing of the stimuli or mismatch of stimuli evenwithout delay. Examples of mismatches are seen in persons suffering fromvertigo or persons in a virtual space such as a video game or flightsimulator or targeting system. A solution is needed that will enable aperson to participate in activities where visual scene motion does notevoke illusory self-motion or motion sickness and participate in motionprovocative activities without having motion sickness, spatialdisorientation, vertigo and loss of human performance activities.

There is a need for improvements to systems and methods that avoidvertigo, motion sickness, and spatial disorientation integrated inmotion sensory provocative environments to avoid problems associatedwith compromised human performance or even loss of user control. Such animprovement can have application in mitigating, preventing orcontrolling symptoms of motion sickness, simulation sickness, gamingsickness, spatial disorientation, dizziness, 3-D vision syndrome orvision induced motion sickness in the environments of 3-D or 4-D motionviewing, or viewing any stereoscopic displays such as with operation ofremote devices, in simulators, medical imaging, surgical training oroperations, virtual environments, scientific visualization, space use,or with gaming devices. An ideal device would be as simple and low costas possible to broaden its market appeal. It should be able to operatein any kind of lighting environment ranging from broad daylight tonighttime conditions. Ideally, the device would not require any powersource.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading the followingdetailed description of non-limiting embodiments thereof, and onexamining the accompanying drawings, in which:

FIG. 1A. is a front view of a pair of eyeglasses having a set ofmechanical pendulums that move with pitch and roll of a user's head;

FIG. 1B is a side view of the eyeglasses of FIG. 1A;

FIG. 2A is a front view of the eyeglasses of FIG. 1A when the user'shead is rolled to down to the user's left;

FIG. 2B is a front view of the eyeglasses of FIG. 1A when the user'shead is pitched forward;

FIG. 3A is a front view of the eyeglasses of FIG. 1A when the user'shead is rolled to the user's right and the user's head is pitchedforward;

FIG. 3B is a side view of the eyeglasses of FIG. 1A when the user's headis rolled to the user's right and the user's head is pitched forward;

FIG. 4A is an alternate embodiment of a pair of eyeglasses having a setof mechanical pendulums that move with pitch and roll of a user's head;

FIG. 4B is a front view of the eyeglasses of FIG. 4A when the user'shead is pitched forward and rolled to the user's right;

FIG. 5A is another embodiment of a pair of eyeglasses having a set ofmechanical pendulums that move with pitch and roll of a user's head;

FIG. 5B is a front view of the eyeglasses of FIG. 5A when the user'shead is pitched forward and rolled to the user's right;

FIG. 6A is an embodiment of a pair of eyeglasses having a set ofmechanical pendulums for roll without having a mechanism for detectingor presenting pitch information;

FIG. 6B is a front view of the eyeglasses of FIG. 6A when the user'shead is pitched forward and rolled to the user's left;

FIG. 7A is a front view of a pitch and roll indicating pendulum deviceintegrated into a helmet;

FIG. 7B is a front view of the device of FIG. 7A with the user's headpitched forward and rolled down to the user's left;

FIG. 8A is a front view of an alternate embodiment of a pitch and rollindicating pendulum device integrated into a helmet;

FIG. 8B is a front view of another embodiment of a pendulum deviceintegrated into a helmet that only provides roll feedback;

FIG. 9A is a front view of a pendulum-based device integrated into ahelmet that only provides pitch visual feedback to the user;

FIG. 9B is a front view of the device of FIG. 9A with the user's headpitched forward and rolled down to the user's left;

FIG. 10A is a front view of a pendulum device that can be clipped ontoanother head-worn device such as a helmet or glasses; and

FIG. 10B is a side view of the clip-on device of FIG. 10A;

FIG. 11A. is a front view of a pair of eyeglasses having two rollingelements that move with roll of a user's head;

FIG. 11B is a front view of the eyeglasses of FIG. 11A when the user'shead is rolled down to the user's left;

FIG. 12A. is a front view of the glasses of FIG. 11A that also include apendulum mechanism and artificial horizon in the left lens to providepitch information;

FIG. 12B is a side view of the eyeglasses of FIG. 12A;

FIG. 13A is a front view of the glasses of FIG. 12A with the user's headpitched backwards;

FIG. 13B is a side view of the glasses of FIG. 13A with the user's headpitched backwards;

FIG. 14A. is a front view of a pair of eyeglasses having a fluid levelthat moves with pitch and roll of a user's head;

FIG. 14B is a side view of the eyeglasses of FIG. 14A;

FIG. 15A is a front view of the eyeglasses of FIG. 14A when the user'shead is pitched forward;

FIG. 15B is a front view of the eyeglasses of FIG. 14A when the user'shead is rolled to the left;

FIG. 16A is an alternate embodiment of the a pair of eyeglasses having afluid level that moves with pitch and roll of a user's head;

FIG. 16B is a side view of the eyeglasses of FIG. 16A;

FIG. 17A shows the embodiment of FIG. 16A when the user's head ispitched backward;

FIG. 17B shows the embodiment of FIG. 16A when the user's head is rolledto the left;

FIG. 18A shows a front view of a pair of eyeglasses that uses a lens tofocus on a fluid-filled roll sensor;

FIG. 18B shows a top view of the embodiment of FIG. 18A;

FIG. 19A shows the use of a mirror and a lens to focus at a shortdistance and in a different orientation from a viewer's normal line ofsight;

FIG. 19B shows the use of a concave mirror to focus at a short distanceand in a different orientation from the viewer's normal line of sight;

FIG. 19C shows the use of a concave mirror to focus at a short distancein the viewer's normal line of sight;

FIG. 20A shows a top schematic view of a housing that holds a lens, afluid filled chamber, and reticle, wherein the housing is mounted in aneyeglass;

FIG. 20B shows a front view of the embodiment of FIG. 20A;

FIG. 20C shows the embodiment of FIG. 20A and FIG. 20B when the user'shead is rolled to one side;

FIG. 21A shows a top view of an embodiment using a mirror, lens, balland reticle to provide both pitch and roll information off-bore of auser's normal line of sight;

FIG. 21B shows a detail side view of the optical path in the orientationmodule used by the embodiment shown in FIG. 21A;

FIG. 21C shows a bottom view of the orientation module of FIG. 21B;

FIG. 22A shows a top view of an embodiment using rear view mirrors andthe orientation module shown in FIG. 21B; and

FIG. 22B shows a side view of an embodiment using rear view mirrors andthe orientation module shown in FIG. 21B.

It should be understood that the drawings are not necessarily to scale.In certain instances, details that are not necessary for anunderstanding of the invention or that render other details difficult toperceive may have been omitted. It should be understood that theinvention is not necessarily limited to the particular embodimentsillustrated herein.

DETAILED DESCRIPTION

The ensuing description provides preferred exemplary embodiment(s) only,and is not intended to limit the scope, applicability or configurationof the disclosure. Rather, the ensuing description of the preferredexemplary embodiment(s) will provide those skilled in the art with anenabling description for implementing a preferred exemplary embodiment.It should be understood that various changes could be made in thefunction and arrangement of elements without departing from the spiritand scope as set forth in the appended claims. Specific details aregiven in the following description to provide a thorough understandingof the embodiments. However, it will be understood by one of ordinaryskill in the art that the embodiments may be practiced without thesespecific details.

Embodiments of the present invention comprise head worn devices andmethods for mitigating or preventing motion sickness. Motion sicknesscan include vertigo, simulation sickness, gaming sickness, spatialdisorientation, dizziness, vision induced motion sickness or vectioninduced motion sickness in 2-D, 3-D, or 4-D environments, including theviewing of displays such as with operation of remote devices, invehicles, simulators, medical imaging, surgical training or operations,virtual environments, scientific visualization, space use, orentertainment, such as gaming. Some embodiments of the present inventioncan operate without any electricity, electronics, or active componentsthat consume power. For example, some embodiments of the presentinvention have no video engine and no battery and use only passivedevices with one or two axial orientations to prevent and control motionsickness, motion-induced vision sickness, and other variants of spatialdisorientation and vertigo. Embodiments of the present invention can useno electrical signals. Embodiments of the present invention can usepurely mechanical devices instead of electro-mechanical sensors ortransducers that convert movement to an electrical signal such asaccelerometers, gyroscopes, acoustic sensors, magnetic sensors, andoptical sensors. Instead, embodiments of the present invention can usepurely mechanical devices such as pendulums, rolling elements, andfluids. Embodiments of the present invention can be implemented withoutusing magnets. Embodiments of the present invention can be head worn(for example, helmets, hats, visors, eyewear, or clip on to helmets,face-shields, etc) or eye worn devices with visual displays that providevisual symbology representing a user's position or orientation. Byvisualizing the information, the sensory mismatch between the sensedlabyrinthine signals, the proprioception and visual perception can becontrolled or mitigated. Embodiments of the present invention can beused in a variety of environments where motion is present or anticipatedor in the presence of provocative visual stimuli. Embodiments of thepresent invention can be used to control symptoms of sickness associatedwith motion in simulated environments or 3-D, 4-D, or 5-D elements,atmospheres, settings, situations, conditions, context, mediums, orenvironments. Embodiments of the present invention can be used tocontrol vertigo for the user who has vertigo, for a person experiencingmotion sickness while riding in a vehicle (such as a boat, car,aircraft), or for someone experiencing visually-induced motion sicknessfrom watching a moving image on a stationary screen. Embodiments of thepresent invention can also be used to mitigate or control spatialdisorientation or motion sickness in gaming devices, in a controller orcomputer format or with simulator use or in a virtual environment or forany simulation sickness. Embodiments of the present invention can alsobe used in rehabilitation environments for balance stabilization orenhancement.

Generally speaking, embodiments of the present invention sense gravity,micro-gravity, some surrogate for gravity (such as a magnetic force), orinertia (such as centrifugal/centripetal force or Coriolis forces) tomove a mechanical element or a fluid in a way that gives a user a visualcue as to his or her orientation with respect to the surroundingenvironment. The cue can be constant. Such cues override thedysfunctional labyrinth, or stimulated labyrinth and mismatched visualinformation received and serve to eliminate the sensory mismatch and theresulting sensations of nausea, emesis, blurred vision, or otherassociated complaints of visual disturbance, headaches, imbalance andloss of human performance activities associated with these variants ofmotion related or visually related sickness, spatial disorientation orvertigo.

Embodiments of the present invention can include an orientationreference symbol or symbols. For example, there can be a horizontalorientation reference symbol that comprises a line that is fixedrelative to the user's head and field of vision, and therefore parallelto the person's interaural axis. This horizontal reference line can thenbe viewed relative to inertial information that can include anartificial horizon. For purposes of this disclosure, pitch can bedefined as rotation of the head about the interaural axis (a lineconnecting the ears) relative to gravity or relative a fixed referenceframe. Synonyms for pitch include azimuth and elevation. For purposes ofthis disclosure, roll can be defined as rotation of the head about thenaso-occipital axis, (a line from the bridge of the nose to thecenter-point of the line connecting the ears) relative to gravity orrelative to a fixed reference frame. The naso-occipital axis (or axis ofrotation for roll) can also be thought of as a line perpendicular to theinteraural axis that lies in a horizontal plane for a person whose headis in a natural upright position. A fixed horizontal line can be used apitch orientation reference symbol, it can be used as a roll orientationreference symbol, or it can be used as both a pitch orientation and aroll orientation reference symbol. A vertical line can also be used asan orientation symbol, and can be a pitch orientation reference symbol,a roll orientation reference symbol, or both a pitch orientation and aroll orientation reference symbol. There can be one or more verticallines. This vertical line or lines can further comprise a verticalscale. There can be separate orientation reference symbols for each eye.A dot can also be used as an orientation reference symbol for pitch,roll, or both pitch and roll. More broadly speaking, any other shape orcombination of shapes capable of being understood by anyone skilled inthe art can be used as an orientation reference symbol. Theseorientation reference symbols should be located where they are visibleto the user. The orientation reference symbols can be can be in theperiphery of the user's vision, either on the side or on the top orbottom. The orientation reference symbols can be in the center of theuser's vision. The orientation reference symbols can move from thecenter to the periphery of the user's vision based on inertial or userinput. The orientation reference symbols are fixedly attached or a fixedelement of a device that can be fixedly attached to the user's head.

Embodiments of the present invention may include an inertial horizon(sometimes called an artificial horizon) and other visual cues toproduce a stable site of visual fixation relative to the user's actualpitch and roll motion. The visual cues may be symbols of any type orshape capable of being understood by anyone skilled in the art. A singlevisual cue can be used for both pitch and roll or there can be separate(independent) visual cues for pitch and for roll. The visual cues canmove in a way that provides a continuously variable (i.e. analog)reading of pitch and roll for a person. There can be separate visualcues for the right eye and the left eye. The visual cues should belocated to be visible to the user. The visual cues can be in theperiphery of the user's vision, either on the side or on the top orbottom. The visual cues can be in the center of the user's vision. Thevisual cues can move from the center to the periphery of the user'svision based on inertial or user input. The visual cues are a part ofthe device that can be fixedly attached to the user's head.

Embodiments of the present invention may be worn on the head and as theuser moves, the pitch and roll indicators move respectively. It has beendocumented with several studies that such feedback controls or mitigatessensory mismatch between the labyrinth/vestibular, visual andproprioceptive systems, so as to give relief to those people whoexperience motion sickness, spatial disorientation or suffer vertigo andcan help to provide visual feedback to those people undergoingrehabilitation for balance stabilization, control or enhancement. Inparticular, it is possible to provide visual feedback that matches thevestibular pitch and roll information for a healthy normal person. Thissatisfies a long existing need for a mechanical system capable ofcontrolling the sensory mismatch, which is induced by environmentalconditions or labyrinthine/vestibular system dysfunction, orstimulation, visual disturbance or provocative stimulation ordysfunction of proprioceptive response or stimulation. It can bepresented in a monocular or binocular fashion and it is inexpensive andcan eliminate the need for a video engine, a power supply, andelectronics of any kind. It should be noted that many embodiments of thepresent invention do not include any reference information for yaw (i.e.rotation about an vertical axis for a person standing upright), theprimary axes of rotation for embodiments of the present invention arepitch and roll.

Embodiments of the present invention may be implemented in ways thatmakes the cues visible in bright light or in darkness. The visual cuescan be located so they do not interfere with vision (e.g. the user cancontinue to see through the display to see other objects or performother tasks—it is available to the user upon need). One analogy is thatof looking at a baseball game through a wire fence in that after momentsof focusing on the play action the fence is not noticed, but upon needthe fence can be focused upon.

Embodiments of the present invention may include symbology. Of criticalimportance to success of the system is the symbology of the cuesprovided to the user to prevent, avoid, and ameliorate motion sickness,spatial disorientation or vertigo. Not only is the information providedimportant but also experience demonstrates that the way in whichinformation is presented is critical to successful use of the system.The following describe embodiments of symbology that has beendemonstrated to be successful. Many factors are important to the successof the cue symbology such as, shape(s), color(s) and dynamicmechanization(s) of the symbology as used in various embodiments forvarious applications.

The artificial horizon or inertial horizon provides the user with astable position on which to focus when experiencing symptoms of motion.If vertigo is present the user can focus on this stable line or can morespecifically focus on a point on this line, such as a center point or anoff-bore point, with the fovea of the eye. When focusing on this point,the effects of pitch and roll motion are decreased and the user can thenhave increased cognitive task performance as a result of lessening thevisual-vestibular conflict.

Embodiments of the present invention may include a roll indicator thatcan enhance proprioception by visual confirmation of head and bodylocation and movement. The combination of an inertial horizon and a rollindicator also confirms what the inner ear and the proprioception havesensed when there is no or limited visual reference, such as indarkness, or when the visual information is misleading. In the absenceof vision, the head is not able to maintain a stable position.Labyrinth-defective subjects use proprioceptive cues to perceive bodyposition. In vibration or provocative motion environments theproprioceptive system is decrease. The particular combinations ofsymbology and symbology elements and functions may vary. The variety mayin whole or in part be driven by the application in which the embodimentis intended for use.

Embodiments of the present invention may include either an Offset or aBore Sight Display. The location of the symbology may be offset from thecenter bore sight to allow the user to better see through the displayand to enhance compatibility with other optical displays such ashead-mounted displays or night vision equipment and symbology such asfire control targeting symbology. In one embodiment the symbology ispresented off bore sight to one side or the other (preferably to theleft for the left eye or to the right for the right eye. When thesymbology is displayed off bore sight, it may be shrunk to fit. In someembodiments, the symbology can still however be set on bore-sight takingthe same view-space of his other instruments if desired by the user.

Embodiments of the present invention may include a monocular orbinocular display. The display can be presented to the user either as amonocular or binocular see-through display and can be eye worn, headworn or mounted to a helmet or head worn device.

Embodiments of the present invention may be adaptable to variouscarriers. For example embodiments of the present invention can bedetachably attached to hats, glasses, a helmet, a head-mounted display,binoculars, goggles, scuba masks, face shields, and any other user worndevice. Embodiments of the present invention could also be integratedinto any head-mounted devices such as the ones mentioned in the previoussentence. Embodiments of the present invention can be directly attachedto the head, independent of any other head-worn devices. Embodiments ofthe present invention are typically implemented in the user's viewingregion and within several inches of the eyes. For that reason, theseembodiments typically will include a clear lens or see-through window orshield and these lenses, windows, or shields will typically have anon-opaque region through which the user can see directly ahead. Theselenses, windows, or shields could be made out of glass or a plastic(i.e. polymer) such as polycarbonate, acrylic, or polystyrene, or someblend of multiple polymers. The fabrication of these lenses, windows orshields is something capable of being understood by anyone skilled inthe art.

Referring now to the figures, FIGS. 1A and 1B show an embodiment of thepresent invention that relies exclusively on pendulums. This embodimentis in the form of pitch/roll eyeglasses, shown at 100. These eyeglasseshave been placed on a user's head, shown at 90. The pitch/rolleyeglasses 100 are comprised of a pitch pendulum shown at 102. In theembodiment shown, there are pitch pendulums 102 on the legs on bothsides of the eyeglass frame. The pitch pendulums 102 rotate about aninteraural axis at a pitch pendulum pivot point, shown at 120. The pitchpendulums 102 are coupled to pitch linkages, one of which is shown at106, and the other of which is on the right leg of the glasses. One endof each pitch linkage 106 connects to an inertial pitch horizon bar,shown at 110. In the embodiment shown, there is an inertial pitchhorizon bar 110 for each eye and the two inertial pitch horizon bars 110are connected to each other through an inertial pitch horizon linkage108 that has been shaped to clear the nose for most head orientations.The other side of each pitch linkage 106 is connected to a pitchcounterweight, shown at 112. The pitch counterweights 112 ensure thatthe pitch assembly, comprising items 102, 104, 106, 108, 110, and 112hangs correctly when the user has their head in a level position. Theeyeglasses 100 can also have one or more primary head rotation referencesymbols, shown at 114. In this case, the primary head rotation referencesymbols 114 are circular dots and there are four of them, two for eacheye. Using circular dots for head rotation reference symbols haveexperimentally been found to be useful because they give the user somefixed points to focus on (i.e. eye fixation elements), which canminimize distractions from other things going on in the environment,reduce eye twitching (i.e. nystagmus), and reduce physiological motionsickness, spatial disorientation, etc. The primary head rotationreference symbols 114 are designed to move with the head and theglasses. In this embodiment the primary head rotation reference symbols114 are attached or printed to the lenses of the glasses. The primaryhead rotation reference symbols 114 in this embodiment will appear aboveor below the inertial pitch horizon bar 110 when the user's head ispitched forward or backward, providing a visual signal to the user thathis/her head is pitched forward or backward. It should also be notedthat the pitch pendulum pivot points 120 in this embodiment are locatedto align with the pitch axes of the eyes so that the inertial pitchhorizon bar 110 moves up and down a distance that matches where theuser's visual system would expect a true horizon to be if a persontilted his/her head forward or backward in a gravitational environmentthat was free of other inertial influences (such a centrifugal orCoriolis forces).

The pitch/roll eyeglasses also have roll pendulums, shown at 122. Theembodiment shown has four roll pendulums 122, two for each eye. The rollpendulums in this embodiment are attached to the glasses above thelenses through roll pendulum pivot points, shown at 120. The rollpendulum pivot points 120 allow each roll pendulum 122 to rotate whenthe user's head is rolled about naso-occipital axis. In addition to theprimary head rotation reference symbols 114, there are additional rollreference symbols, shown at 124 that give further indication to theamount of roll of the person's head. In the embodiment show, the rollreference symbols 124 are in the form of vertical lines that align withthe vertical lines of the roll pendulums 122 when the person's head isin a neutral (neither pitched nor rolled) position.

FIG. 2A shows how the visual cues for the embodiment of the pitch/rolleyeglasses 100 shown in FIG. 1A and FIG. 1B change when the user's head90 is rotated (rolled) down to the left. In this case the inertial pitchhorizon bar 110 does not move relative to the user's head when theuser's head is rolled in the absence of any change in pitch. The rollpendulums 122, rotate about the roll pendulum pivot points 120 in orderto continue to align with gravity about the naso-occipital axis. Thiscreates an offset between the roll pendulums 122, and the primary headrotation symbols reference symbols 114 as well as between the rollpendulums 122 and the roll reference symbols 124.

FIG. 2B shows how the visual cues for the embodiment of the pitch/rolleyeglasses 100 shown in FIG. 1A and FIG. 1B change when the user's head90 is rotated (pitched) forward. In this case the inertial pitch horizonbar 110 moves upward in the user's field of view, creating an offsetbetween the primary head rotation reference symbols 114 and the inertialpitch horizon bar 110. The inertial pitch horizon bars rotate about thepitch pendulum pivot points 104. The inertial pitch horizon linkage 108(attaches the inertial pitch horizon bars 110 for each eye to eachother) also moves up the same distance. In this embodiment, the rollpendulums, 122 do not move when the head is pitched, but not rolled.

FIG. 3A and FIG. 3B show a front and side view, respectively, of theembodiment of the pitch/roll eyeglasses 100 shown in FIG. 1A and FIG. 1Bwhen the head 90 is both rolled to the left and pitched forward. Asshown in FIG. 3A, both the inertial pitch horizon bar 110 and the rollpendulums 122 move relative to the primary head rotation referencesymbol 114 when the head is both pitched and rolled. The side view shownin FIG. 3B illustrates how the pitch pendulum 102 continues to hangvertically below the pitch pendulum pivot point 104 and how this causesthe inertial pitch horizon linkage 108 (as well as the inertial pitchhorizon bars 110, which are difficult to see in this view) to moveupward relative to the eyeglass lenses. The roll pendulum pivot points120 move with the eyeglass lenses as the head is pitched forward andbackward about the interaural axis. When looked at from a side view, theroll pendulums 122 appear not to move.

Further referring to the figures, FIGS. 4A and 4B show an alternatepitch/roll pendulum eyeglass embodiment at 400 mounted on a user's head90. The alternate eyeglasses 400 have alternate roll pendulums 422hanging from alternate roll pendulum pivot points 420 attached toalternate inertial pitch horizon bars 410. In this alternateconfiguration, the alternate pendulums 422 move up and down as theuser's head 90 is pitched forward or backward as well as rolling whenthe user's head rolls.

FIGS. 5A and 5B show another pitch/roll pendulum eyeglass embodiment at500 mounted on a user's head 90. These other eyeglasses 500 have otheranother roll pendulum 522 hanging from another pivot pendulum point 520that is attached to another horizontal bar 510. This other eyeglassembodiment 500 also has horizontal roll pendulum linkages 526 and uses ahorizontal line positioned on each lens as another primary head rotationreference symbol 514.

FIGS. 6A and 6B show roll-only pendulum eyeglasses 600 mounted on auser's head 90. These roll-only pendulum glasses 600 have four roll-onlypendulums 122 that are connected through four roll pendulum pivot points120 to the frame of the eyeglasses in a manner similar to that shown inFIG. 1A. These roll-only pendulum glasses 600 also have roll referencesymbols 124 that are similar to those of FIG. 1A. The embodiment shownin FIGS. 6A and 6B uses an alternate embodiment of a primary headrotation reference symbol 614 in the form of an open circle that moveswith the lenses of the glasses. Note that the pendulums shown in FIG. 6Bcan also be called plumb bobs. It is also worth pointing out that thesependulum or plumb bobs could also be immersed in a liquid by, forexample, combining elements of the embodiment shown in FIG. 6A and FIG.6B with elements of the fluid-filled embodiments shown in FIGS. 14A-17B.

FIGS. 7A and 7B show an embodiment of the present invention in the formof a pitch/roll pendulum helmet at 700 mounted on a user's head 90. Inthis embodiment, an arrangement similar to the one shown in FIG. 5A andFIG. 5B has been mounted onto a helmet 702. The FIG. 7A shows a frontview of this embodiment 700 in a neutral (no pitch and no roll)configuration. FIG. 7B shows this embodiment 700 in a configurationwhere the user's head is pitched forward and rolled to the left.

FIG. 8A shows an embodiment of a pitch-roll pendulum helmet at 800 thatincorporates the features of the alternate pitch/roll eyeglasses thatwere shown in FIG. 4A and FIG. 4B. This illustrates that is possible toincorporate many of the same features of the embodiments for eyeglassesinto embodiments for helmets. It should further be noted that there aremany more head worn articles that can incorporate the mechanical pitchand roll systems described here including visors, face shields, baseballcaps, and any other head-worn item capable of being understood by anyoneskilled in the art.

FIG. 8B shows an embodiment of a single primary head rotation referencesymbol helmet 850 that provides pitch and roll information in the formof a single unit inertial pitch horizon bar 856 that pitches and rollsas a single unit across both eyes. This configuration 850 can beimplemented through the use of a pendulum and a pivot aligned with thenaso-occipital axis at the back of the head or through the use ofrolling elements in the helmet linked to rotate the single unit inertialpitch and roll linkage 856 about the naso-occipital axis that arecoupled to a pendulum hanging below the chin.

FIGS. 9A and 9B show an embodiment of a pitch-only helmet at 900. Thispitch-only helmet 900 is similar to other embodiments shown in previousfigures, but does not have any mechanism or symbology to display roll.This can be seen by comparing the pitch only helmet 900 on a user's head90 that is in a neutral position (no pitch and no roll) in FIG. 9A, withthe same pitch only helmet 900 on the user's head 90 when the head 90 ispitched forward and rolled left.

FIGS. 10A and 10B show another embodiment of the present invention inthe form of a pitch/roll pendulum clip-on at 1000. The clip-on 1000functions similarly to the alternate pitch/roll eyeglasses embodimentshown in FIG. 5A and FIG. 5B, without the eyeglasses. FIG. 10A shows aview of the clip-on 1000 in an orientation equivalent to looking at auser's face from the front and FIG. 10B shows the same clip-on from theside. The clip-on has the same pitch pendulum pivot point 104 that wasshown and described with reference to FIG. 1A, and the same other rollpendulum point 520 that was shown and described with reference to FIG.5A. The clip-on 1000 can be designed to attach to eyeglasses, helmets,face shields, a person's ears, baseball caps, visors, headbands, or anyother device capable of being understood by anyone skilled in the art.

FIGS. 11A and 11B show an embodiment of the present invention in theform of roller eyeglasses at 1100. The roller eyeglasses use a rollingelement 1130 that is retained in a track 1132 to keep the rollingelement 1130 adjacent to one or both of the lenses in a pair ofeyeglasses. The roller eyeglasses 1100 can also incorporate indicatorline primary head rotation reference symbols, shown at 1114. FIG. 11Bshows that rolling of the user's head 90 (to the left in this case) willresult in the rolling elements 1130 moving relative to the indicatorline primary head rotation reference symbols 1114, providing the userwith visual feedback of inertial head rotation in the roll direction.The rolling elements 1130 can be of any shape that rolls and is capableof being understood by anyone skilled in the art. Examples includespheres (or balls), cylinders, cones, any other shape that isrotationally symmetric about an axis of rotation.

FIG. 12A and FIG. 12B illustrate a compound mechanical pitch/rolleyeglasses 1200 that combine the rolling elements 1130 of FIG. 11A andFIG. 11B with a pitch indicator inertial pitch horizon bar 110 (andrelated pendulum-based actuation elements) of FIG. 1 as well as theprimary head rotation reference symbol 114 for one eye that is similarto that of FIG. 1. A secondary head rotation reference symbol 1214 inthe form of an etched line in the lens of the glasses is alsoillustrated in the embodiment of FIG. 12A. FIG. 12B provides a side viewof the embodiment of FIG. 12A and this side view also shows the track1132 that retains the rolling element 1130, which was also discussed,but not shown, with reference to FIG. 11A and FIG. 11B. FIG. 13A andFIG. 13B shows a front view and a side view, respectively, of thecompound embodiment 1200 with the user's head pitched backward.

Embodiments of the present non-electronic system and method can alsoincorporate fluids, such as gases an/or liquids, to provide a visualindication of what the vestibular system should be sensing. These fluidsystems can also incorporate floats. Fluid based systems can bemechanically simple and the fluid interface, a float or floats, or apendulum/plumb bob immersed in the fluid can provide a direct visualindication of the gravitational pull and/or inertia being experience bya user. Selection of the viscosity of the fluids and size of theplumbing can provide as much or as little damping as might be desired.

Referring to FIG. 14A, FIG. 14B, FIG. 15A, and FIG. 15B, a pair offluid-level pitch/roll eyeglasses is shown at 1400. The fluid-leveleyeglasses 1400 incorporate a first fluid shown at 1402 and a secondfluid shown at 1404 that have a fluid-fluid interface shown at 1406. Thefirst fluid 1402 is typically a liquid and the second fluid 1404 caneither be a liquid having a lower density than the first fluid 1402 or agas. The first fluid could be transparent, translucent, or opaque. Thesecond fluid could be transparent, translucent, or opaque. Thefluid-fluid interface 1406 may incorporate a float (not shown) that canhelp increase visibility of the height of the first fluid 1402. Theembodiment of the fluid level eyeglasses shown at 1400 uses two cleartubes, one for each eye, shown at 1408 that are located in the user'speripheral vision. The clear tubes are connected to two reservoirs 1410located on the temples of the eyeglasses in the embodiment shown. Eachclear tube 1408 has two connections to its proximate reservoir 1410. Oneof these connections is a first fluid-reservoir connection 1412 thatconnects the bottom of the right or left clear tube 1408 with the bottomof the right or left reservoir. The other is a second fluid-reservoirconnection 1414 that connects the top of the right or left clear tube tothe top of the right or left reservoir. In the embodiment shown in FIG.14A, FIG. 14B, FIG. 15A, and FIG. 15B, there are also tworeservoir-reservoir connections that run behind the user's head. One ofthese is a first reservoir-reservoir connection 1416 that connects thebottom of the right reservoir to the bottom of the left reservoir. Theother is a second reservoir-reservoir connection 1418 that connects thetop of the right reservoir to the top of the left reservoir. Thisembodiment also has a primary head rotation reference symbol 1420 in theform of a scale with horizontal lines placed adjacent to each of the twoclear tubes in a location visible to the user. The head rotationreference symbols 1420 will move with the eyeglasses, which move withthe head. As shown by FIG. 15A, forward pitch of the head causes thefluid-fluid interface 1406 to rise in the clear tubes 1408 providingvisible feedback to the user that the head has pitched forward. Theamount of vertical movement of the fluid-fluid level in the clear tubes1408 as a result of changes in pitch can be controlled in the design ofthis embodiment through the sizing and placement of the reservoirsrelative to the clear tubes. If the clear tubes and the reservoirs havethe same cross sectional areas and the reservoirs are located an equaldistance behind the center point of the users eyeballs as the cleartubes are in front of the user's eyeballs, the amount of rise and fallof the fluid-fluid interface will correspond with an inertial horizon(i.e. a gravitational artificial horizon if the user is not moving).Increasing the cross sectional area of the reservoirs increases theamplification factor in the clear tubes and decreasing the crosssectional areas decreases the amplification factor. Moving thereservoirs further behind the center point of the users eyeballsincreases the amplification factor and moving the reservoirs closer tothe center point of rotation about the interaural axis decreases theamplification factor. As shown by FIG. 15B, rotation to the left causesthe fluid-fluid interface to rise in the left clear tube 1406 a and fallin the right clear tube 1406 b providing visible feedback to the userthat the head has rotated to the left.

FIG. 16A, FIG. 16B, FIG. 17A, and FIG. 17B, illustrate an alternatefluid-level eyeglass embodiment at 1600. The alternate fluid-levelembodiment 1600 has replaced the tubes 1408 of FIG. 14A withfluid-filled windows, shown at 1608. The fluid-filled windows 1608 canhave the advantage of more clearly providing visual roll information tothe user. They can have the disadvantage that seeing through a liquidcan create visually disturbing refraction effects. This alternateembodiment uses the same concepts of a first fluid 1402, a second fluid1404, and a reservoir 1410. There is a first fluid window-reservoirconnection 1612 and a second fluid window-reservoir connection 1614.There is also a first fluid window-window connection 1616 and a secondfluid window-window connection 1618 across the bridge of the eyeglassesbecause this is more convenient than using reservoir-reservoirconnections across the back of the head as was done in the embodimentshown in FIG. 14A, FIG. 14B, FIG. 15A, and FIG. 15B. FIG. 17A and FIG.17B also illustrate that this alternate embodiment uses an alternateprimary head rotation reference symbol in the form of a horizontal lineetched across the two lenses in the eyeglasses. It should be note thatthe location of the fluid-fluid for this alternate embodiment does notneed to be in the center of the user's line of sight when the user'shead is in a neutral (no pitch and no roll) position. The fluid-fluidinterface in the neutral position could also be below (or above) thecenter of the user's line of sight. It should also be noted that thesame principles apply in selecting the size and location of thereservoirs in order to provide amplification of the response of thealternate fluid level embodiment to pitch as apply to the embodimentshown in FIG. 14A through 15B.

It should further be noted that concepts illustrated for the fluid-levelbased eyeglasses can also be used in other head-mounted devices such ashelmets and face shields. It is possible to combine elements of thefluid filled embodiments with elements of the roll-element basedembodiments and/or the pendulum-based embodiments. For example it ispossible to use a fluid-based element (such as a liquid-containingwindow) for roll and a pendulum for pitch. It is also possible to usemany of the primary head rotation reference symbols or secondary headrotation reference symbols with many of the embodiments. It is alsopossible to build compound embodiments in which a float in a fluid-levelsystem is attached to a linkage that is mechanically coupled to avisible symbol.

It is further possible to implement an embodiment in which the rollindicator is in a separate head worn unit for each eye. For example,contact lenses that have been weighted to orient (as those used forastigmatism) can also have symbology in the form of horizontal orvertical lines or a translucent or transparent region in them to providepitch feedback to a user. In this case, the reference symbology that isfixed to the user's head may be in a head-worn unit that is separatefrom the contact lenses. It may further be feasible to make contactlenses that respond to pitch of the eyes to provide pitch informationthat can also be referenced by the user to a head-worn unit thatprovides a pitch orientation reference.

The embodiments shown in the attached figures can be illuminated invarious ways so that the technology can be used in low levels of light,bright sunlight or darkness. The Embodiments of the present inventioncan use fiber optics plus tritium, which does not require battery power,other radiochemcials with illumination tubes or chambers. If a batteryor solar cell is utilized LEDs can be utilized. If no battery is usedsuch methods as tritium illumination can be used. Tritium illuminationis the use of gaseous tritium, a radioactive isotope of hydrogen, tocreate visible light. Tritium emits electrons through beta decay, andwhen they interact with a phosphor material, fluorescent light iscreated, a process called radioluminescence. As tritium illuminationrequires no electrical energy, it found wide use in applications such asemergency exit signs and illumination of wristwatches. More recently,many applications using radioactive materials have been replaced withphoto-luminescent materials. Tritium lighting is made using glass tubeswith a phosphor layer in them and tritium gas inside the tube. Such atube is known as a “gaseous tritium light source” (GTLS), or beta light,(since the tritium undergoes beta decay). The tritium in a gaseoustritium light source undergoes beta decay, releasing electrons, whichcause the phosphor layer to fluoresce. During manufacture, a length ofborosilicate glass tube which has had the inside surface coated with aphosphor-containing material is filled with the radioactive tritium. Thetube is then fused with a CO₂ laser at the desired length. Borosilicateis preferred for its strength and resistance to breakage. In the tube,the tritium gives off a steady stream of electrons due to beta decay.These particles excite the phosphor, causing it to emit a low, steadyglow. Tritium is not the only material that can be used for self-poweredlighting. Other beta particle-emitting radioisotopes can also serve.Radium was used in the past to make self-luminous paint, but has beenreplaced by tritium, which is less hazardous. Various preparations ofthe phosphor compound can be used to produce different colors of light.Some of the colors that have been manufactured in addition to the commonphosphorus are green, red, blue, yellow, purple, orange, and white. Thetypes of GTLS used in watches give off a small amount of light—notenough to be seen in daylight, but enough to be visible in the dark froma distance of several meter. The average such GTLS has a useful life of10-20 years. As the tritium component of the lighting is often moreexpensive than the rest of the watch itself, manufacturers try to use aslittle as possible. Being an unstable isotope with a half-life of 12.32years, tritium loses half its brightness in that period. The moretritium that is initially placed in the tube, the brighter it is tobegin with, and the longer its useful life. Tritium exit signs usuallycome in three brightness levels guaranteed for 10, 15, or 20 year usefullife expectancies. These light sources are most often seen as“permanent” illumination for the hands of wristwatches intended fordiving, nighttime, or tactical use. They are additionally used inglowing novelty key chains and in self-illuminated exit signs. They arefavored by the military for applications where a power source may not beavailable, such as for instrument dials in aircraft, compasses, andsights for weapons. Tritium lights are also found in some old rotarydial telephones, though due to their age they no longer produce a usefulamount of light. Tritium lights or beta lights were formerly used infishing lures. Some flashlights have slots for tritium vials so that theflashlight can be easily located in the dark. Tritium is used toilluminate the sights of some small arms. The electrons emitted by theradioactive decay of the tritium cause phosphor to glow, thus providinga long lasting (several years) and non-battery-powered firearms sightwhich is visible in dim lighting conditions. The tritium glow is notnoticeable in bright conditions such as during daylight however. As aresult, some manufacturers have started to integrate fiber optic sightswith tritium vials to provide bright, high-contrast firearms sights inboth bright and dim condition Because tritium in particular is anintegral part of certain thermonuclear devices (though in quantitiesseveral thousand times larger than that in a keychain), consumer andsafety devices containing tritium for use in the United States aresubject to certain possession, resale, disposal, and use restrictions.Devices such as self-luminous exit signs, gauges, wrist watches, etc.,which contain small amounts of tritium are under the jurisdiction of theUS Nuclear Regulatory Commission, and are subject to possession,distribution, import and export regulations found in 10 CFR Parts, 30,32 and 110. They are also subject to regulations for possession, use anddisposal in certain states. They are readily sold and used in the US andare widely available in the UK and are regulated in England and Wales byenvironmental health departments of local councils. Tritium lighting islegal in most of Asia and Australia. While these devices contain aradioactive substance, it is currently believed that self-poweredlighting does not pose a significant health concern. Encapsulatedtritium lighting devices, typically taking the form of a luminous glasstube embedded in a thick block of clear plastic, prevent the user frombeing exposed to the tritium at all unless the device is broken apart.Tritium presents no external radiation threat when encapsulated innon-hydrogen-permeable containers due to its low penetration depth,which is insufficient to penetrate intact human skin. The primary dangerfrom tritium arises if it is inhaled, ingested, injected or otherwiseabsorbed into the body. This results in the emitted radiation beingabsorbed in a relatively small region of the body, again due to the lowpenetration depth. The biological half-life of tritium—the time it takesfor half of an ingested dose to be expelled from the body—is low, atonly 12 days. Tritium excretion can be accelerated further by increasingwater intake to 3-4 liters/day. Direct, short-term exposure to smallamounts of tritium is relatively harmless. If a tritium tube shouldbreak, one should leave the area and allow the gas to diffuse into theair. Tritium exists naturally in the environment, but in very smallquantities. Options include tiny gas lights (borosilicate glasscapsules). Some watches are advertised to possess “always visibletechnology.” The watch hands and markers contain tritium insets whichprovide permanent luminescence, as opposed to phosphorescent markersused in other watches, which must be charged by a light source. Thetritium in a gaseous tritium light source undergoes beta decay,releasing electrons which cause the phosphor layer to fluoresce. Duringmanufacture, a length of borosilicate glass tube which has had theinside surface coated with a phosphor-containing compound is filled withthe radioactive tritium. The tube is then fused with a CO₂ laser at thedesired length. Borosilicate is used for its strength and resistance tobreakage. In the tube, the tritium gives off a steady stream ofelectrons due to beta decay. These particles excite the phosphor,causing it to emit a low, steady glow. Tritium-filled luminous tubesentered the market in the '90s, and while their multi-year illuminationmakes them a good choice, their relatively low brightness can bedifficult to see in partially lit conditions, or immediately aftermoving from a brightly lit to a dark environment. Starting in 2003,Reactor developed a proprietary method of applying a unique Swissmaterial called Superluminova that makes other watches the brightest andlongest-lasting phosphorescent watches in the world. However, whileSuperluminova is at least five times brighter than tritium after beingcharged in the light, that brightness fades to below that of tritiumover several hours. Never Dark™ was the first technology to combine theintense brightness of Superluminova with the multi-year longevity oftritium, providing optimal illumination under all lighting conditions.Because it can take up to 30 minutes for the human eye to fully adjustto the dark, Superluminova's intense peak brightness makes a Never Dark™watch easily visible during that initial period. This can be even moreimportant when moving repeatedly from light to dark (such as when goingbelow deck on a boat during the day), as the Superluminova willcontinually recharge and the eye will not have time to adjust. Insituations where the watch will remain in the dark for many hours, thetritium will remain visible for years, even if the watch is neverreturned to the light. While tritium remains at a constant level,Superluminova gets extremely bright then fades over several hours, butrecharges very quickly when re-exposed to light. Never Dark® is the onlywatch illumination to “self-adjust” to conditions, with a response curvesimilar to that of the human eye. At its peak, the glow of Superluminovais easily visible, even at dusk or in difficult, partially litconditions. With a full charge, it produces five to ten times the lightoutput of tritium. But, as that brightness fades, the tritium willcontinue to glow for at least ten years. Unlike radioactive isotopesthat have been used on watches in the past, tritium poses no health riskto the wearer or to the workers who assemble the watches. Tritium'sradioactive decay produces only weak beta particles that are containedcompletely within the sealed glass tubes. Even if exposed, the betaparticles do not possess enough energy to penetrate the outer layer ofhuman skin.

Embodiments of the present invention can further include one or moreoptical elements. The term optical element as used in this disclosureincludes lenses, mirrors, prisms, beam splitters, retro-reflectors,fluids, other transmissive or transparent media, and any other devicethat can change the appearance or apparent location of an image. Theoptical elements can have a variety of coatings. The optical elementscan be used in variety of combinations. The optical elements may havesurfaces that are flat, concave, convex, and/or any other shape capableof being understood by anyone skilled in the art. The optical elementscan be used for a variety of functions including focusing and/ordefocusing. As examples of combinations, embodiments of this inventioncan use single or multi-element mirrors, single or multi-element lenses,combinations of a mirror or mirrors with a lens or lenses, andcombinations of a mirror or mirrors and/or a lens or lenses, with otheroptical elements, such as those elements previously described.

Lenses are transmissive optical elements or modules that use refractionto affects the focus of a light beam. A lens can focus light to form animage, unlike a prism, which refracts light without focusing or a mirrorwhich reflects light. A simple lens consists of a single piece ofmaterial. Simple lenses can be subject to optical aberrations which canbe compensated for by using a combination of simple lenses withcomplementary aberrations. A compound lens is a collection of simplelenses of different shapes and made of materials of different refractiveindices, arranged one after the other with a common axis. One of thereasons that lenses might be combined is that whatever good theperformance of an aspheric lens may be in monochromatic light, it cannotcover wide spectral range because refractive index of glass varies withwavelength, causing chromatic aberration. The common solution to thisproblem is the so-called achromatic doublets, which is a pair ofcemented convex and concave lenses of different refractive indices. Theachromatic doublet may be designed either for best chromaticcompensation or for best spherical aberration performance.

A lens or lenses can be used to facilitate close distance focusing onthe symbology described earlier in this disclosure. There are a manydifferent lens configurations available which can provide a focusedcentral image. It can be desirable to keep the mounting of the deviceclose to the eye and avoid a large projection away from the eye and lenssurface. To accomplish this, the lens can have a more complex designproperty and multiple lenses can be used, mounted together or separatedfrom each other. A mirror, prism, or beam splitter can also be used toproject the image to the visual field and in combination with the lensor lenses.

To maintain required features of the displayed image or symbology, thelens or lenses can move in response to gravity. This can be accomplishedby having a weighted lens or lens assembly, with the heavier componenton the bottom that is mounted in a way that it can rotate on bearingsthat have little to no friction. The lens could rotate relative to theframework with “frictionless” bearings, as the head or body rotates, toalways provide a true horizontal area, which the user can focus on whenexperiencing motion or motion sickness. Alternatively, fluid can be usedin combination with a lens to visualize the image, which remainshorizontal with pitch and roll movements.

Achromatic Lenses are examples of lenses used to minimize or eliminatechromatic aberration caused by light at different frequencies that arebent differently by the index of refraction of a lens composed of onlyone material. Achromatic Lenses are ideal for a range of applications,and often designed by either cementing two elements together or mountingthe two elements in a housing. Achromatic lenses can be used to createsmaller spot sizes than comparable chromatic lenses.

Aspheric Lenses can be preferable lenses and are used to eliminatespherical aberration in a range of applications, including bar codescanners, laser diode collimation, or OEM or R&D integration. Lensconfigurations which include an aspheric lens can provide excellentcentral resolution of the visualized image at a closer focal distancefrom the eye than an equivalent spherical lens. Aspheric lenses canaccomplish more in a single element design than spherical lenses, whichhelps minimize the number of lenses found in multi-lens opticalassemblies. Aspheric lenses have a more complex front surface thatgradually changes in curvature from the center of the lens out of theedge of the lens. In an aspheric lens the surface of the lens is “foldedopen” in the peripheral areas so that the surface structure deviatesfrom the spherical shape. All rays coming from the distance meet againat one point. The spherical aberration is corrected. A positive sideeffect of this flattening is that it leads to thinner and lighterlenses. This effect is most evident with high plus powers. In this case,the reduction of the center thickness also leads to a reducedmagnification effect. An aspheric lens can be coated with a range of theUltraviolet (UV) spectrum, visible light, or Infrared (IR) spectrum.

The aspheric lens can be mounted in a lightweight holder to minimizesize and weight. This assembly can further include a reticle, featureand/or other images or symbology. The lens assembly can be incorporatedin a transparent plastic lens framework. The lens aperture may vary from4 mm to 10 mm. If a reticle is incorporated, the reticle diameter isalso variable, but generally can be 6-6 mm to allow adequate field ofview. The lens and other optical elements can be attached to the eyewearor can be incorporated into the eyewear. A clip on feature can allow theassembly to be closer to the pupil when needed. If the assemble inincorporated into the lens it can move/slide into a more appropriateposition when needed. This would then accommodate the eye/pupil positionto enhance human performance. Specifically this can be done with ahousing for fitting an aspheric lens and modified reticle.

Regardless of the optical element or combination of optical elementsused the goal of the optical assembly is to provide a clear picture ofthe symbology/image/feature/reticle visualized to mitigate the symptomsof motion sickness/dizziness/disorientation. The eye worn device canthen be worn in any environment, whether it be virtual, augmented, reallife or in active situational activities.

Beam-splitters are another optical element that can be used inembodiments of the present invention. The two most commonly used typesof beam-splitters are the beam-splitting plates and cubes. Generally,they are designed for 45 angle of incidence and transmission ratios50/50, 70/30, or 90/10%. The beam-splitting cubes may be eitherpolarizing or non-polarizing. The beam-splitting plate has only threeadvantages over the cube: lower price, less aberration when installed ina converging beam, and possibility to completely eliminate the ghostbeam when the plate has a wedge. Aberration is smaller simply becausethe plate is much thinner than the cube. In all the other components thecube is better: better spectral uniformity of the reflectioncoefficient, smaller difference between transmission coefficients forsand p-polarization, less ghosting, no displacement, easier to mount,negligible deformation under mechanical stress. In a beam-splittingplate, the beam reflects from the interface between the air andglass—two materials with very different refractive indices (1.0 and1.5).

Reticles. For a person experiencing motion sickness, vision inducedmotion sickness dizziness, disorientation or vertigo, visual fixation ona stable point will mitigate or abort the symptoms. A stable horizontalline has been found to be effective for a person experiencing motionsickness. Embodiments of other optical elements of the present inventioncan utilize a horizontal line, symbols, reticles and/or other featuresand can further include a center mark on the horizontal line for theuser to focus on when experiencing symptoms of motion sickness, visioninduced motion sickness, dizziness, vertigo or disorientation.Additionally, embodiments of the present invention can provide pitch androll information about the user's position to enhance the user'sorientation in space. The horizontal area will always remain horizontaland enable the user to focus on a stable point of reference. Thishorizontal line can be comprised of symbols, features and/or lines andmay resemble the cross hairs of a reticle. Reticles may be etched on thelens or/lenses.

Etched glass reticles can have floating elements (such as circles ordots), which do not cross the reticle. Reticles can have complexsections designed for other use. Reticles can be printed or etched on atransparent material such as glass or plastic. Reticles on a transparentmaterial can be less durable than wire reticles, and the surface of thetransparent material can reflect some light (about 4% per surface onuncoated glass) lessening transmission through the lens system, althoughthis light loss is near zero if the glass is multi-coated. Thehorizontal line or reticles may be illuminated, either by a plastic orfiber optic light pipe collecting ambient light. Some illuminationsources can use the radioactive decay of tritium for illumination, whichcan work for 11 years without using a battery. Red is the most commoncolor used for illumination, as it is the least destructive to the nightvision, but some can use green or yellow illumination, either as asingle color or changeable via user selection. The reticle may belocated at the front or rear focal plane (First Focal Plane (FFP) orSecond Focal Plane (SFP) and multiple lenses, beam splitters or mirrorsmay be used to adjust the focal length.

FIG. 18A and FIG. 18B show an embodiment of the present invention thatuses a lens. FIG. 18A is a front view and FIG. 18B is a top view. In theembodiment shown at 1800, the lens housing 1801 is mounted in a pair ofglasses 1802. The lens body 1801 comprises a lens (not visible in theseviews) that bends the optical path 1803 to allow the user to focus on abubble 1804 in a liquid reservoir 1805. The advantage of the embodimentshown in FIG. 18A and FIG. 18B over the embodiments previously shown isthat a user can more easily focus on the orientation indicator, a fluidfilled roll sensor in this example. It should be noted that this conceptof using a lens to focus at short distance could be applied to all ofthe embodiments previously described in this disclosure.

FIG. 19A, FIG. 19B, and FIG. 19C show three types of reflector sightsthat produce virtual images of reticles. FIG. 19A uses a collimatinglens (CL), shown at 1903, and a beam splitter, shown at 1902, tosuperimpose an apparent virtual image at infinity, shown at 1905, of anactual image, shown at 1904, of a reticle. FIG. 19B uses a half silveredconcave mirror (CM), shown at 1906, as the collimating optics to view anactual image 1904 that is an offset. FIG. 19C uses a half silveredconcave mirror (CM) 1906 as the collimating optics with the actual image1904 between the mirror and the observer. Apparent images 1905 ofcollimated reticles such as those shown in FIG. 19A, FIG. 19B, and FIG.19C are produced by non-magnifying optical devices such as reflectorsights (often called reflex sights) that give the viewer an image of thereticle superimposed over the field of view, and blind collimator sightsthat are used with both eyes. Collimated reticles are created usingrefractive or reflective optical collimators to generate a collimatedimage of an illuminated or reflective reticle.

Reflector sight or reflex sight is another optical element device thatallows the user to look through a partially reflecting glass element andsee an illuminated projection of an image superimposed on the field ofview. These sights work on the principle that anything at the focus of alens or curved mirror (such as an illuminated reticle) will look like itis sitting in front of the viewer at infinity. Reflector sights employsome sort of “reflector” to allow the viewer to see the infinity imageand the field of view at the same time, either by bouncing the imagecreated by lens off a slanted glass plate, or by using a mostly clearcurved glass reflector that images the reticle while the viewer looksthrough the reflector. Since the reticle is at infinity, it stays inalignment with the device the sight is attached to regardless of theviewer's eye position, removing most of the parallax and other sightingerrors found in simple sighting devices. The image is reflected off someform of angled beam splitter or the partially silvered collimatingcurved mirror itself so that the observer (looking through the beamsplitter or mirror) will see the image at the focus of the collimatingoptics superimposed in the sight's field of view in focus at ranges upto infinity. Since the optical collimator produces a reticle image madeup of collimated light, light that is nearly parallel, the light makingup that image is parallel with the axis of the device it is alignedwith, i.e. with no parallax at infinity. The collimated reticle imagecan also be seen at any eye position in the cylindrical volume ofcollimated light created by the sight behind the optical window.

FIG. 20A shows a top schematic view of a housing 1801 that holds a lens1903, fluid-filled chamber 2002, and a reticle, wherein the housing 1801is mounted in an eyeglass, shown at 2001. The optical path 1803 from auser's eye 1901 to the fluid-filled chamber 2001 is also depicted inFIG. 20A. FIG. 20B shows a front view of the embodiment of FIG. 20A andFIG. 20C shows this front view when the user's head is rolled to oneside. In addition to the elements shown in FIG. 20A, the two front viewsshown in FIG. 20B and FIG. 20C also show the relationship between thefluid 2002 and the reticle 2003 when the user's head is rolled to oneside. The reticle 2003 rolls with the head and the fluid 2002 stayslevel due to gravity or inertia. In the system shown in FIG. 20A, FIG.20B, and FIG. 20C, the housing 1801 can be transparent and just largeenough to hold the lens 1903, which is convex. The lens could be 6 mmand is there to allow the eye 1901 to focus at a close distance on thereticle 2003 and the level of the fluid 2002. The reticle 1801 could bean image on the reticle or on one of the transparent or translucentsurfaces of the fluid-filled chamber 2002.

FIG. 21A shows an embodiment using a mirror, lens, ball, and reticle toprovide both pitch and roll information off-bore of the user's normalline of sight. This embodiment, shown at 2100 comprises two orientationmodules, shown from the top at 2101. The optical paths from the user'seyes are shown at 1803. FIG. 21B shows a side view of the orientationmodule 2101 to show how the optical path 1803 from the eye 1901 entersthe housing 1801, is bounced off of a flat mirror 2102, passes through alens 1903 to view a rolling element 1130. The rolling element 1130, inthe form of a sphere, can roll on the convex surface at the bottom ofthe housing to indicate both pitch and roll of the orientation module2101, and therefore the system 2100 and therefore the user's head. FIG.21C shows a bottom view of the orientation module 2101 to illustrate howthe housing of the orientation module 2101 can further comprise areticle 2003 that provides a reference for the location of the rollingelement 1130 as the user's head rotates in the pitch and rolldirections. The housing 1801 could be made out of a Plexiglas or othertransparent material is machined to hold the lens 1903 on one end andthe reticle on the other with the spacing such that the reticle isfocused to the eye. This can be a module approximately 14 mm long thatcould be mounted to eyeglasses in some position off axis to the centralvision. This could be attached to the eyeglasses or incorporated intothe framework or transparent portion of the eyeglasses. The orientationof the mounting can be adjusted to accommodate for the user's anatomy ofthe face and eye position. Specifically, an opening can exist in theplastic or other type of lens of an eyeglass to accept and angularposition the optic at the right distance off axis.

FIG. 22A and FIG. 22B show two views of an embodiment 2200 that usesrear view mirrors 2201 in conjunction with the orientation module ofFIG. 21A, FIG. 21B, and FIG. 21C. By having rear view mirrors 2201, theoptical path 1803 allows for (1) a greater distance between the eye andthe reticle and rolling element, (2) placement of the orientationmodules further back and in a less visually obtrusive location, and (3)the use of two mirrors, which helps to make the motion of the roller inthe housing move in a more intuitive way for the user. Both pitch androll feedback can be provided to the user in this embodiment.

The mounting of the embodiments described here can be in the form of aclip on device to the framework of the eyewear, a fixed or detachablemethod can also be use with a pivot, swivel or tilting mechanism toposition the system or device into the visual field. The device can bepositioned in the central visual field of view or off the central visualfield (e.g. “off bore”). The positioning within the visual field can bemanually selected, adjusted and fixed to the framework of the eyewear.The mounting position can be adjusted to whatever position the userprefers. For example, if the user is experiencing motion sensitivity,the device may be preferred to be positioned more closely to the centerof the visual field and if there is no motion experienced the preferredposition may be “off bore”. The mounting of the system or device canalso be incorporated in the eyewear lens. This can be seen as a fixedmounting through a perforation in the eye worn lens or an opening in thelens of a variable length will allow movement of the device, within thelens, for proper positioning depending on the user's preference and theanatomy of the eye position. The mounting of the device system can alsoallow for tilting anteriorly and posteriorly or laterally (e.g. thedevice can be pitched forward or backward and can be rolled to eitherside) in order to position the visualized image well. Inertial mountingof the system device can also allow the viewed horizontal image to moveas the head rolls to the right or left. When the head rolls to the lefthorizontal image can be seen to remain horizontal. The mounting of thedevice can also allow for adjustments in focal length, if the focallength needs to be changed.

Additional further embodiments can include:

-   A. A feature to manually adjust focal length;-   B. Operation that comprises the ability to detect at least 30    degrees of pitch and 30 degrees of roll;-   C. A feature that provides pitch and roll data;-   D. The incorporation of multiple lenses, mirrors, prisms, and/or    split beams to provide a clear image to the user;-   E. The use of frictionless ball bearings or fluids to maintain the    horizontal line/image/feature/symbology in a horizontal plane-   F. An opening in the lens that can provide a method of sliding    adjustment for positioning of the device, to move it either into    “bore site or off bore site”;-   F. A configuration in which only the horizontal image is seen in the    lens and the frame of the system and/or eye wear provides pitch and    roll information; and-   G. A configuration in which the device is combined with an    electronic head-worn eye tracker, head tracker, a head-worn display,    and/or transducers capable of obtaining and displaying biometric    information.

Applications for the present technology can include a variety ofprovocative motion environments such as vehicle use, an AR (augmentedreality environment), a multi-dimensional environment, a synthetic orcomputer generated synthetic environment, and/or a visual inducedenvironment, such as watching motion while the user is motionless. Amore detailed description of some of these examples and some otherexamples are:

-   A. Vehicles. The most obvious use for this invention is to prevent    motion sickness, spatial disorientation or visually induced motion    sickness symptoms with any type of vehicular use, whether it moves    on the ground, in air, or on water. In such an environment physical    or visual movement alters our normal sense of perception and visual    causing symptoms of sickness and resulting in loss of human    performance activities or decay in physical and or perceptual    normalcy. Examples of vehicular activities where the invention has    benefit opportunities include:-   (i) Operators and passengers in commercial, general aviation, and    military fixed wing aircraft including tanker, airlift, support, and    fighter aircraft can employ the head-worn, eye-worn embodiments of    the present technology to improve comfort, mission-effectiveness,    and human performance. SD/MS causes degradation of human performance    (affecting cognitive and motor skills), with resultant loss of    expensive equipment and human life. Embodiments of the present    invention can provide the visual cues necessary to combat SD in the    civil aircraft flight environment and control the motion sickness in    the other flight personnel to enhance their human performance.    Passengers in commercial air carriers, business and general aviation    aircraft routinely experience motion sickness from vestibular upset    and loss of visual cues. Embodiments of the present invention can    prevent or lessen the motion sickness/visually induced motion    sickness for passengers aboard all type of civil aircraft.-   (ii) Helicopters. Rotary wing aircraft are particularly capable of    generating high motion provocative environments due to extreme    vibration, the visual flash of the rotor blades in various lighting    conditions and unique maneuvering capabilities. One more specific    example is Flash Vertigo. There are many case examples where    helicopter operators/passengers have encountered extremely adverse    physical effects due to the flickering or flashing of light through    the rotating blades of the helicopter. Some of the most severe have    resulted in motion sickness, spatial disorientation or vertigo. Use    of embodiments of the present invention can reduce the negative    effects associated with the strobe effects of rotor wing vehicles.    It can also help during brown-out when rotary wing operators can    experience loss of visual cues and a sensation of downward velocity    increase and/or disorientation when landing in blowing or loose sand    environments.-   (iii) Ships, boats, and other marine vessels. Sailors stationed    aboard naval ships and merchant marine vessels have long been    susceptible to motion sickness associated with the vessel movements    that occur during aggravated sea states. It is estimated that nearly    every person ever stationed aboard a marine vessel for a prolonged    status has suffered mild to debilitating seasickness. Embodiments of    the present invention can prevent, alleviate, and/or mitigate the    symptoms of seasickness aboard ships. Naval aircrew members assigned    aboard ships who engage in flight simulator training on those ships    often are affected by motion sickness. This occurs because the    motion of the ship and associated vestibular stimulus creates a    mismatch with visual cues viewed in the simulator. Additionally the    simulator results in a loss of visual cues regarding the shipboard    environment. This technology will prevent/mitigate motion sickness    that occurs during shipboard flight simulator training Embodiments    of the present invention can also be effective in controlling motion    sickness associated with leisure ship board cruises.-   (iv) Land vehicles. One example is reading during vehicular travel.    Many people become carsick when sitting in the back of a moving    vehicle with reduced visual cues and increased vibration and even    more still when attempting to read in this motion provocative    environment. Embodiments of the present invention can provide visual    cues to counteract the loss of the normal visual cues that would    mitigate SD/MS, with the stimulation of the inner ear and offset the    effect of vibration in the ground transportation environment-   (v) Space: Micro-gravity and Re-entry Rehabilitation. Embodiments of    the present invention can space sickness by providing visual cues to    offset the loss of proprioception and orientation due to loss of    gravitation. Embodiments of the present invention can also reduce    the time to re-acclimate to the terrestrial environment by providing    strong visual cues to help orientation in conjunction with the    increase in cues provided by reintroduction of gravitation.-   (vi) Theme parks and movie theatres. It is highly common for    tourists visiting theme parks to become disoriented or experience    motion sickness riding them park rides. This is due to the nature of    the attractions themselves that either generate extreme motion    provocative environments or provide visual cues that have the same    effect by using extremely provocative visual displays, simulated    displays, 3-D, 4-D or 5D displays, mirroring or reflection    environments. Embodiments of the present invention can prevent the    associated sickness by providing overriding visual cues that show    the true orientation of the passenger with respect to the ground.    The head/eyewear is effective in countering motion sickness,    visually induced motion sickness, and spatial disorientation in    rides that use high fidelity visual displays since the passenger    would be able to verify his/her actual position.-   (vii) Sports and recreation. In nearly every sports activity that    features the loss of visual cues or motion provocative environment    such as sailing, rock climbing, and auto racing participant's remark    on the loss of situation awareness, disorientation or occasional    motion sickness. It is expected the invention will prevent symptoms    similarly as described above in these environments by providing    strong visual cues to counter the effects of sensory mismatch    associated with these motion provocative environments. Similarly, in    offshore fishing it is highly common for at least one person in the    party of any recreational offshore fishing boat to become seasick.    As with regard to ships and boats, embodiments of the present    invention can be effective in the prevention and control of motion    sickness in person aboard small marine vessels.-   B. Stroboscopic/Stereoscopic viewing. Different types of    stereoscopic display viewing or stroboscopic viewing can induce eye    symptoms as described above and cause sickness symptoms. This    technology can lessen the visual fatigue/visual discomfort and other    visual symptoms as well as the associated visually induced motion    sickness.-   C. Simulators and Displays.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims. For example,embodiments of the present invention can include fluids or pendulums. Anumber of variations and modifications of the disclosed embodiments canalso be used. The principles described here can also be used for otherapplications. While the principles of the disclosure have been describedabove in connection with specific apparatuses and methods, it is to beclearly understood that this description is made only by way of exampleand not as limitation on the scope of the disclosure.

What is claimed is:
 1. A non-electronic system for providing visualorientation information, the system comprising: a head attachment unitconfigured for attachment to a head of a person; an optical elementselected from the group of a lens, a mirror, a beam splitter, and aprism wherein the optical element is configured to be visible to theperson; an orientation reference symbol configured to be visible to theperson when viewing the optical element, wherein: the symbol is fixedlycoupled to movement of the head attachment unit whereby the symbol isconfigured to be in a fixed visual position for the person when theperson's head moves; and the symbol comprises a reference elementselected from the group of a pitch reference element and a roll element;an indicator selected from the group of a pitch indicator and a rollindicator, wherein: the indicator is configured to be visible to theperson when viewing the optical element; the indicator moves in responseto rotation of the head attachment unit about an orientation selectedfrom the group of an interaural axis and a naso-occipital axis of theperson; the indicator is responsive to an inertial device selected fromthe group of a pendulum attached to the unit, a rolling element retainedin the unit, and two fluids in a reservoir in the unit; movement of theindicator does not comprise a response from an electro-mechanical sensorselected from the group of an accelerometer, a gyroscope, an acousticdetector, a magnetic detector, and an optical detector; and movement ofthe indicator does not require the use of electricity; and movement ofthe indicator occurs in a normal field of view of the person.
 2. Thesystem of claim 1 wherein the system is suitable for use in a vehicle.3. The system of claim 1 wherein the system does not use a magnet. 4.The system of claim 1 wherein the symbol further comprises an eyefixation element whereby the person can focus on the eye fixationelement to minimize a physiological effect selected from the group ofvertigo, motion sickness, vision-induced motion sickness, motionintolerance, and spatial disorientation resulting from sensory mismatchbetween a person's visual, vestibular, and proprioceptive organs.
 5. Thesystem of claim 1 wherein: the unit comprises a head-worn moduleselected from the group of eyeglasses, a helmet, and a face shield; thehead-worn module comprises a non-opaque region through which a personcan see directly ahead; and the non-opaque region comprises a materialselected from the group of glass and a polymer.
 6. The system of claim 1wherein the indicator is detachably attached to the unit.
 7. The systemof claim 1 wherein: the optical element further comprises: a left eyeoptical element; and a right eye optical element; the orientationreference symbol further comprises: a left eye orientation referencesymbol selected from the group of a left eye pitch reference element anda left eye roll reference element; and a right eye orientation referencesymbol selected from the group of a right eye pitch reference elementand a right eye roll reference element; the indicator further comprises:a left eye indicator selected from the group of a left eye pitchindictor and a left eye roll indicator; and a right eye pitch selectedfrom the group of a right eye pitch indicator and a right eye rollindicator; whereby the person can receive visual inertial headorientation information for the left eye and the person can receivevisual inertial head orientation information for the right eye.
 8. Thesystem of claim 1 wherein the indicator further comprises both a pitchindicator and a roll indicator.
 9. The system of claim 8 wherein thepitch reference element comprises a line substantially parallel with theinteraural axis.
 10. The system of claim 8 wherein the pitch indicatorcomprises a pendulum and the roll indicator comprises a pendulum. 11.The system of claim 8 wherein the pitch indicator comprises a pendulumand the roll indicator comprises a rolling element.
 12. The system ofclaim 8 wherein the pitch indicator and the roll indicator comprise afirst fluid and a second fluid wherein: the first fluid comprises aliquid; and the first fluid has a higher density than the second fluid.13. The system of claim 12 wherein the second fluid comprises a gas. 14.The system of claim 12 wherein the second fluid comprises a liquid. 15.The system of claim 12 wherein the first fluid comprises a translucentliquid.
 16. The system of claim 12 wherein the first fluid comprises anopaque liquid.
 17. The system of claim 12 wherein the orientationreference symbol further comprises: a left eye orientation referencesymbol; and a right eye orientation reference symbol; the pitchindicator and the roll indicator further comprise: a combined pitch androll indicator for the left eye comprising a left visible fluid filledreservoir configured to be in a field of view of the person's left eye;and a combined pitch and roll indicator for the right eye comprising aright visible fluid-filled reservoir configured to be in a field of viewof the person's right eye; and the system further comprises: a leftpitch reservoir configured to be located on the head of the person andbehind the left visible fluid filled reservoir; a right pitch reservoirconfigured to be located on the head of the person and behind the rightvisible fluid filled reservoir; a fluid connection between a lowerregion of the left visible reservoir and a lower region of the leftpitch reservoir; a fluid connection between an upper region of the leftvisible reservoir and an upper region of the left pitch reservoir; afluid connection between a lower region of the right visible reservoirand a lower region of the right pitch reservoir; and a fluid connectionbetween an upper region of the right visible reservoir and an upperregion of the right pitch reservoir.
 18. The system of claim 17 wherein:the left visible fluid filled reservoir is located in a region proximateto a bottom of the person's left eye field of view; the right visiblefluid filled reservoir is located in a region proximate to a bottom ofthe person's right eye field of view; the left eye orientation referencesymbol further comprises a horizontal line substantially parallel to theperson's interaural axis; and the right eye orientation reference symbolfurther comprises a horizontal line substantially parallel to theperson's interaural axis.